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Currently, the fault warning technology for the cutting part of cantilever roadheader relies on traditional data collection methods. In the operation process of the cutting part of the roadheader, problems such as difficulty in obtaining signals and high noise limit the capability to predict and warn faults in the cutting part of the roadheader. In order to solve the above problems, a fault warning method for the cutting part of cantilever roadheader based on virtual and real fusion data is proposed. The method performs three-dimensional solid modeling of the cutting section of a cantilever roadheader. It uses the automatic dynamic analysis of mechanical systems (ADAMS) to obtain virtual data of the cutting section's mechanical system, constructs its dynamic simulation model to obtain virtual data. The method uses the cosine similarity function to characterize its similarity with real data to verify the credibility of the virtual data. The method uses Bayesian estimation and adaptive complementary weighted fusion methods to perform similarity association and complementary association fusion on virtual and real data, respectively, to obtain virtual and real fusion data. In response to the problem that the learning efficiency of traditional self-organizing mapping (SOM) neural networks is easily affected by the learning rate, a fault warning model based on an improved SOM neural network is established. A monotonic decreasing function about time is introduced to train the SOM neural network, ensuring both the learning rate and the stability of the model. The method inputs the fused data into the fault warning model based on SOM neural network to determine the winning neuron and adjust its weight. The method calculates the distance between the real data and the winning neuron and adjusts its weight to achieve fault warning. The experimental results show that the average operating efficiency of the improved SOM neural network can be improved by 35.84%. The fault warning method for the cutting part of a cantilever roadheader based on virtual and real fusion data can successfully predict the types of single and composite faults, with a prediction accuracy of 83.33%.

The existing boom-type roadheader cutting control adopts a relatively simple control method and the cutting head completes the roadway section cutting at a constant speed. There's no comprehensive consideration of trajectory planning and autonomous speed control. Therefore, it is difficult to achieve high roadway engineering quality under complex geological conditions. In order to solve the above problems, a boom-type roadheader autonomous speed regulation cutting control system is proposed. Firstly, the three-dimensional model of the cutting head and coal seam are established and imported to ABAQUS software for finite element analysis. The relationship between the reaction force on the cutting head and the swing speed of the cutting arm is obtained. Then the relationship between the swing speed of the cutting arm and the acceleration of the cutting head is obtained. The acceleration is stratified by k-means clustering method. Secondly, the collision detection model of the cutting head is established by using the bounding volume hierarchy algorithm. The appropriate cutting trajectory of the rectangular roadway section is planned. The discrete cutting path planning points are generated through multiple discretizations. The inverse kinematics solution of the cutting arm is calculated to obtain the rotation radian, lifting radian and elongation of the cutting arm required for the cutting head to reach the discrete cutting path planning point. The global optimal speed model is used to solve the speed of the cutting head to move to the discrete cutting path planning point. Finally, the acceleration sensor is used to collect the vibration signal of the cutting arm. The target swing speed of the cutting arm is determined according to the acceleration layering result. Through fuzzy PID control, the swing speed of the cutting arm is adjusted to the target swing speed in time and accurately with the change of the cutting head acceleration. The experimental results show that the fuzzy PID control can achieve a relatively fast and non-overshoot swing speed adjustment of the cutting arm. Compared with the constant speed cutting control, the roadway section forming quality using the autonomous speed control cutting control is high. The width specification deviation is reduced by 37%, and the height specification deviation is reduced by 17%. The results meet the requirements of roadway forming quality specified in MT/T 5009-1994 Standard for quality inspection and assessment of coal mine roadway engineering.

Aiming at the problems of high labor intensity, low degree of automation and low positioning accuracy of single way in the construction process of existing coal mine anchor digging machine, a long-distance positioning system suitable for anchor digging machine is developed by using sensor measurement, machine vision, inertial navigation and other technologies. The system consists of anchor digger, inertial positioning subsystem, visual positioning subsystem, total station positioning subsystem and parameter monitoring subsystem. Anchor digger main machine adopts MB670-1 anchor digger; the inertial navigation and positioning subsystem is composed of built-in optical fiber inertial navigation and explosion-proof computer. The visual positioning subsystem includes infrared explosion-proof target, laser pointing device, front explosion-proof industrial camera and explosion-proof computer. The positioning subsystem of total station consists of 360° prism, three laser pointing instrument and rearview prism. Parameter monitoring subsystem includes parameter display, parameter setting and parameter solution module. The system was successfully developed and tested in Dahaize Coal Mine of China National Coal Group. The experiment shows that the long-distance high-precision positioning system of the all-in-one anchor digger has the advantages of flexible operation and highpositioning accuracy, and can realize the positioning and parameter monitoring of the all-in-one anchor digger.

A growing body of research focuses on individual environmental consciousness as an alternative and complement to regulatory and economic policy strategies for sustainable development. However, existing studies failed to explain the complex associations between individual environmental consciousness and conservation practices. This study constructs a framework of environmental prefigurative politics - technologies of the self (EPP-TS) to investigate how the mobilization of technologies of the self can lead to the subjectivization of individual environmental consciousness, thus enabling environmental prefigurative politics to shape specific conservation practices. First, this study argues that a range of technologies of the self, including discursive, incentive, and disciplinary technologies, are mobilized to subjectivize individual environmental consciousness. Second, the subjectivization of individual environmental consciousness prompts and institutionalizes the improvisation of environmental prefigurations, embodying the political imaginaries and power structures that environmental prefigurative politics aspire to realize in society. Third, environmental prefigurative politics also influence the development pathways and situated agency of nature conservation, thereby shaping specific conservation practices. Finally, this study also critiques the environmental prefigurative politics under authoritarian environmentalism, as it also reinforces authoritarian power in subjectivizing individual environmental consciousness. [ABSTRACT FROM AUTHOR]

A new field plate (FP) is proposed for gallium nitride high‐electron‐mobility transistors (HEMTs). It features an innovative arcuate end (AE), which allows the induced charges that originally gathered at the FP end to diffuse over a wider area. Hence, not only is the electric field in the channel at the gate edge alleviated due to the induced charges, but also that concentrated at the FP end is reduced by means of AE. The simulation results indicate that by upgrading a source FP with AE, HEMT gains a 99% increase in breakdown voltage while remaining unaltered in specific on‐resistance. It also gets a 43.41% decrease in power loss during one cycle while maintaining the same breakdown voltage, which greatly contributes to enhance the efficiency of power electronic circuits. [ABSTRACT FROM AUTHOR]

Ecological engineering (EE) has a profound impact on land-use dynamics, leading to alterations in ecosystem services (ESs). However, an appropriate EE implementation intensity that can balance the tradeoffs associated with altered ESs well has always been a concern for researchers and policymakers. In this study, we set the transition probability of farmland, bare land, and desertification land to forest and natural shrub, with 2010–2020 as the natural implementation scenario, as 10% for the low-intensity implementation scenario (LIS), 30% for the medium-intensity scenario, and 50% for the high-intensity scenario. The patch-generating land-use simulation (PLUS) model was used to project land-use patterns and the Integrated Valuation of Ecosystem Service and Tradeoffs (InVEST) model was used to simulate changes in the quality of ESs under four EE implementation intensities in 2030. We then performed a quantitative tradeoff analysis on the dominant ESs under four scenarios and used the production possibility frontier (PPF) curve to identify the optimal EE implementation intensity scenario. Our results indicated that an increase in EE implementation intensity would lead to an increase in soil retention, water purification, habitat quality, and carbon storage, but also to a decrease in water yield, aggravating the tradeoffs between water yield and other ESs. In all EE implementation intensity scenarios, the LIS had the lowest tradeoff intensity index and balanced ESs well, and thus was the optimal EE implementation scenario in Qinghai province. Our results provide knowledge to help decision makers select the appropriate EE intensity to maintain sustainable development. The integrated methodology can also be applied in other conservation regions to carry out practical land management. [ABSTRACT FROM AUTHOR]