Abstract:To address the issue of premature convergence associated with the rapid convergence characteristic of the Particle Swarm Algorithm(PSO),an Improved Particle Swarm Algorithm(IPSO)is proposed.Firstly,to enhance the diversity of the algorithm,a novel dynamic inertia weight method and an adaptive acceleration co-efficient are introduced to dynamically adjust the search range of particles.Secondly,a new speed update strat-egy is presented,which fully utilizes the information from high-quality solutions to further enhance the conver-gence speed of the algorithm.Finally,to verify the effectiveness of the IPSO algorithm,five standard functions were employed for testing,and the results demonstrated its superiority Moreover,the improved algorithm also yielded optimal results in addressing the energy-saving optimization problem of Automatic Train Operation(ATO)for urban rail transit trains.

Abstract:The failure of the section coal pillar due to the coupled effect of mining disturbance and water seep-age weakening is a significant contributor to water inrush accidents in roadways.Exploring the instability char-acteristics and optimal width of the section coal pillar is crucial for effective mine water prevention and control.This paper focuses on the study of the coal pillar in the gob-side entry driving section of the water-bearing goaf area.A fluid-structure interaction numerical calculation model of the section coal pillar is established u-sing FLAC3D,which reveals the coupled characteristics of stress,plastic zones,and water seepage zone within the coal pillar under the influence of mining,water immersion weakening,and roadway excavation.Additional-ly,the stability characteristics of coal pillars with varying widths are compared.The results show that:Under the superimposed effect of overburden pressure and water pressure from the goaf,the coal body on the water-immersed side of the coal pillar is the first to fail.As water accumulates and infiltrates,the elastic modulus,co-hesion,and internal friction angle of the coal body in the water seepage zone decrease correspondingly.The lifecycle of the coal pillar can be divided into three stages:"mining of the upper working face,infiltration of water from the goaf,and roadway excavation."Based on this,it is proposed that the connection between the plastic zone and the water seepage zone should be considered the critical condition for the coal pillar.When the width of the coal pillar is 3 m and 5 m,the plastic zone connects,forming a water conduction channel.However,when the width of the coal pillar is 7 m,9 m,and 11m,the water seepage zone does not connect to the plastic zone,and the coal pillar maintains bearing and water-resisting characteristics.Finally,after emplo-ying a 7 m coal pillar in the field,the maximum roof subsidence observed is 146 mm,demonstrating effective roadway control.

Abstract:In response to the problem of poor surrounding rock control and economic drawbacks of employing a single support scheme for the lower roadway due to significant variation in the thickness of the interlayer in close range coal seams,this paper focuses on the lower mining roadway of a close range coal seam in the San-hekou Coal Mine.Utilizing theoretical analysis,numerical simulation,and on-site monitoring,the study inves-tigates the maximum damage depth and distribution of the interlayer in the roof of the roadway.Based on the thickness and damage characteristics of the interlayer,the roadway is categorized into three zones:the fracture instability zone,the crack damage zone,and the slightly damaged stable zone,with corresponding support schemes proposed for each.The reliability of the zoned support scheme is validated through numerical simula-tion and on-site monitoring results.The research results show that:first,the depth of damage to the bottom plate of the goaf is approximately 5.17m;second,the integrity of the inter layer increases with thickness;and third,the zoned support scheme effectively controls on the surrounding rock.These research findings provide valuable guidance for the design of zoned support in close range coal seam mining and for enhancing economic benefits.

Abstract:In response to the multi factor coupling effect on the heat transfer performance of buried pipes in shallow ground source heat pump systems,this paper focuses on the dual objectives of"influencing factors of buried pipes"and"heat transfer performance".A three-dimensional numerical model was constructed using ANSYS fluid dynamics software to systematically quantify the influence of multiple parameters,including inlet flow velocity,pipe diameter,and thermal conductivity of backfill materials on the heat transfer characteristics of buried pipes.Utilizing the Taguchi experimental design method,a total of 27 orthogonal experiments were con-ducted with 7 factors and 3 levels.Through signal-to-noise ratio analysis and analysis of variance,significant differences and optimal level combinations of various parameters were identified under different evaluation indi-cators,namely inlet and outlet temperature difference,linear heat transfer,and system coefficient of performance(COP).The research indicates that the inlet flow rate has the most substantial impact on the inlet and outlet temperatures(contributing 32.6％)and system COP(contributing 30.7％),while the pipe diameter is the critical factor determining the unit heat transfer per linear meter(contributing 28.9％).The optimal pa-rameter configuration for three typical operating conditions were obtained through multi-objective optimization:the inlet and outlet temperature difference optimization group(A3B2C1D1E3F3G1),unit heat transfer optimi-zation group(A1B2C3D1E3F3G3),and the system COP optimization group(A1B3C3D3E3F2G2).This ap-proach provides a technical pathway for the multi-objective optimization of the system.

Abstract:In response to the problems of broken surrounding rock and the susceptibility of the roof to collapse in the goaf of fault zone roadways,this study focuses on the track downhill roadway of the 25th mining area of Changcun Coal Mine as the engineering context.We propose an advanced support technology that integrates anchor rod sealing and grouting during roadway excavation.This innovative approach combines advanced an-chor rod prestressing with surrounding rock grouting to establish a reinforced roof zone ahead of the excavation face,thereby enhancing the stability of the roof in the goaf area.Furthermore,we derive the relationship be-tween critical grouting pressure and effective sealing lengthby incorporating the characteristics of a bag-type sealing structure.Numerical simulations indicate that the implementation of this advanced support technology results in a 58％reduction in the displacement of the roadway roof and a 68％reduction in the surrounding rocks.Additionally,the depth of the plastic zone in the roof decreases from 1.7 m to 0.7 m.Field industrial tests and mining pressure monitoring reveal that the deformation of the roof rock separation in the advanced support section is significantly less than that in the conventional support section.The axial force of the anchor rod and cable stabilize at approximately 15.8 kN and 132.2 kN,respectively,representing reductions of 70％and 36％.Consequently,the safety factor of the roadway is significantly improved.Thus,the advanced anchor rod sealing and grouting reinforcement technology for the roof of fault fracture zone roadway is advantageous for ensuring safe and efficient operations in these challenging environments.

Abstract:During the mining process,the F13 and F13-1 faults were exposed at the S5207 working face of Yu-wu coal industry.The presence of fault structures disrupts the continuity of the coal rock mass in the working face,leading to a significant decrease in the stability of the surrounding rock.This situation poses risks of coal wall fragmentation,roof instability,and even the potential for rockburst disasters.To safely traverse the fault zone,two-component chemical grouting materials are selected,and intermittent grouting technology is employed to reinforce the fractured rock mass within the fault zone.Monitoring results from two measuring points,namely deep hole and shallow hole,using a borehole stress meter,indicate that the impact range of the F13-1 fault during mining at the working face is between 30 and 40 meters,with relatively concentrated stress,reaching a maximum of 18 MPa.The stress anomaly is particularly pronounced when mining approaches within 30 meters of the F13-1 fault.The monitoring results further demonstrate that during the process of advancing through the fault zone at the working face,the surrounding rock in the mining area remained relatively stable,thereby achieving safe production.

Abstract:Tunnel excavation in weak surrounding rock masses is susceptible to geological hazards such as stra-tum settlement and surface collapse.Grouting reinforcement is frequently utilized in engineering practice to en-hance rock mass strength.The injection of cement grout under pressure into the surrounding rock increases its strength upon hardening,with the water-cement ratio significantly affecting the mechanical properties of the grouted zone.This study examines weak surrounding rock in tunnels by preparing cement grouts with varying water-cement ratios(ranging from 1∶1 to 2∶1)for soil reinforcement.Direct shear tests were performed to as-certain the shear strength parameters(internal friction angle and cohesion)of improved soils.The obtained data were subsequently incorporated into an ABAQUS-based numerical model for analyzing tunnel excavation-induced settlement.Key findings include:(1)The shear test results indicate that soil strength is enhanced post-grouting,revealing an inverse relationship between water-cement ratio and shear strength;(2)Grouting reinforcement effectively mitigates excavation-induced settlement,with the 1∶1 water-cement ratio resulting in a surface settlement of 8.22 mm,which complies with code requirements.These findings provide theoretical guidance for grouting design in conditions of weak surrounding rock.

Abstract:The Permanent Magnet Synchronous Motor(PMSM)speed control systems typically calculate d-q axis current references directly using torque formulas,but these methods are sensitive to motor parameters and struggle to operate at the optimal working point.Sensorless control often employs high-frequency sinusoidal in-jection,but the use of filters reduces system bandwidth and response speed.This paper proposes a composite control strategy that integrates sensorless position estimation via high-frequency square-wave injection and Maximum Torque Per Ampere(MTPA)control based on virtual square-wave injection.The strategy applies virtual square-wave-injected MTPA to control the motor,injects high-frequency square waves into the current loop,and extracts rotor position information from the high-frequency current signals,achieving composite control of the PMSM.Simulation results verify the effectiveness of the proposed control strategy.The speed control system of a permanent magnet synchronous motor(PMSM)typically employs the torque formula to di-rectly compute the reference value for the d-q axis current.However,this method is sensitive to motor parame-ters and poses challenges in achieving optimal operating points.Sensorless control often utilizes the high-fre-quency sine wave injection method,but the implementation of filters can diminish the system's bandwidth and response speed.This paper proposes a novel composite control strategy that integrates the Maximum Torque Per Ampere(MTPA)derived from sensorless position observation with virtual square wave injection,achieved through the application of high-frequency square wave inputs to the permanent magnet synchronous motor con-trol system.In this approach,the motor is regulated by the MTPA introduced by the virtual square wave.The high-frequency square wave is injected into the current loop,allowing for the extraction of rotor position infor-mation from the high-frequency current signal,thereby facilitating the composite control of the PMSM.The ef-fectiveness of the proposed control strategy is validated through simulation results.

Abstract:To mitigate the fire hazard associated with the room-and-pillar old goaf in shallow-buried deep coal seams,a combination of underground mobile liquid CO2 pressure injection and long-distance liquid CO2direct injection is employed to achieve effective long-distance liquid CO2 mobile injection.Following the injection of 16 tons of liquid CO2 into the goaf,the concentrations of O2 and CO were reduced to normal levels prior to oxi-dation,while C2H4 was eliminated.Simultaneously,the concentration of CO2 increased,and the concentration of N2 decreased.During the injection process,the temperature in the old goaf area experienced a significant decrease in a short period,followed by a subsequent rise in temperature.The injection of liquid CO2 effectively controlled coal oxidation in the old goaf area.

Abstract:Emergency science popularization(ESP)serves as a critical factor influencing the advancement of emergency management.In the context of global climate change and the increasing frequency of natural disas-ters,ESP has become a pivotal approach for enhancing public capabilities in disaster prevention and mitigation.However,the evaluation of its effectiveness lacks scientific and systematic methodologies.This study employs the Analytic Hierarchy Process(AHP)as the core methodology,integrating existing practices and future development trends of ESP to construct a multi-dimensional evaluation system consisting of one objective layer,4 first-level criterion layers,13 second-level criterion and 45 indicator.Judgment matrices were established through expert scoring,followed by weight calculations for indicators at each hierarchical level and consistency checks.The results indicate that this system effectively quantifies the evaluation of both soft-ware and hardware development aspects of ESP,thereby providing a scientific foundation for optimizing emer-gency science popularization initiatives.

Abstract:When Chinese enterprises encounter overseas security threats and need to evacuate,establishing an emergency plan is essential to ensure the smooth return of personnel.This paper employs system dynamics the-ory to investigate the emergency evacuation process through system simulation.By applying the principles of system dynamics,it analyzes the key factors influencing the evacuation process,examines the causal relation-ships among the variables in the model,and elucidates the mathematical relationships and equations that govern these variables.Utilizing the Vensim software platform,a system dynamics model for the emergency evacuation of overseas Chinese enterprises is developed,followed by simulations to observe the variations in the evacuation process under different conditions.The findings indicate that the model is effective for risk prediction and effi-ciency evaluation of emergency evacuations,providing a theoretical foundation for overseas security managers to devise rational evacuation plans.

Abstract:To reveal the laws of fault activation and stress evolution during the mining of a fully mechanized top-coal caving face influenced by a fault group,this study utilized the 924 mining face of Zhongmei Dongpo Coal Industry Co.,Ltd.in Shanxi as the engineering context.Field measurements were conducted to investi-gate the activity characteristics of the fault group under mining influence.Borehole stress monitoring technology was employed,with 16 measurement points arranged in the return airway of the working face,enab-ling real-time acquisition of stress change data in the coal and rock mass on the coal wall side.In conjunction with displacement monitoring of the hanging wall and footwall of the faults,the activation characteristics of the fd28 fault and the N13 fault were analyzed.The research results indicate that:influenced by mining,the stress in the rock strata near the fd28 and N13 faults changed significantly,with a peak vertical stress reaching 9.07 MPa.Surface cracks on the faults gradually propagated,with the maximum displacement of the fd28 fault measuring 9 mm,while that of the N13 fault reached 39 mm,demonstrating clear activation effects.The fault activation effect was most pronounced when the working face advanced to within 20to 30 m of the faults.The fd28 fault tended to stabilize after 32 days of monitoring.These research findings provide a theoretical basis and practical reference for understanding the mechanism of fault activation and for the safety management and control of fault groups under mining conditions.

Abstract:Earthquakes are among the most prevalent natural disasters,and the liquefaction of sand and soil in-duced by seismic activity can result in significant casualties and substantial property damage.At present,the increasing accumulation of waste rubber poses a considerable environmental challenge.To investigate the po-tential of sandy soil mixed with rubber particles(hereinafter referred to as'rubber sand')in the context of seismic engineering,this paper examines the liquefaction characteristics of rubber sand through dynamic triaxial tests.The test were conducted on three different sizes rubber particles:fine,medium and coarse.Furthermore,the study considers the effects of three variables:the proportion of rubber particles(0％,10％,20％,and 30％),loading frequency(0.5Hz,1.0Hz,and 2.0Hz),and initial effective confining pressures(50kPa,100kPa,and 150 kPa)on the liquefaction performance of rubber sands.The results showed that the incorporation of rubber particles significantly enhanced the liquefaction resistance of the sand.The number of vibrations required for liquefaction increased nonlinearly with the addition of rubber particles.Specifically,when the incorporation a-mount was within 20％,the increase in the number of vibrations was slight;however,once it exceeded 20％,the number of vibrations required for liquefaction increased significantly.Additionally,the effect of mixing larger rubber particles(coarse)was found to be more pronounced.As the loading frequency increased,the number of vibrations required for liquefaction of rubber sand also increased,while the pore water pressure accumulation rate slowed down,thereby enhancing liquefaction resistance.Furthermore,with an increase in the initial effec-tive perimeter pressure,the number of vibrations required for liquefaction increased significantly.For the three rubber particle sizes-fine,medium and coarse-the number of vibrations required for liquefaction at an initial effective perimeter pressure of 150 kPa increased linearly with the increase in peripheral pressure.These find-ings provide a foundational basis for optimizing waste rubber resource utilization technology and enhancing the seismic capacity of sandy soil foundations.