The accumulation and release of deformation energy within the rock mass of a roadway are primary contributors to the occurrence of rock bursts.This study introduces a calculation model for the kinetic energy generated...The accumulation and release of deformation energy within the rock mass of a roadway are primary contributors to the occurrence of rock bursts.This study introduces a calculation model for the kinetic energy generated during roadway excavation,which is based on the fracture and energy states of the rock mass.The relationships among the mining depth,width of the plastic zone,rebound range of the roof and floor,stress concentration factor,and the induced kinetic energy are systematically explored.Furthermore,a rock burst risk evaluation method is proposed.The findings indicate that the energy evolution of the rock mass can be categorized into four stages:energy accumulation due to in-situ stress,energy accumulation resulting from coal compression,energy dissipation through coal plastic deformation,and energy consumption due to coal failure.The energy release from the rock mass is influenced by several factors,including mining depth,stress concentration factor,the width of the plastic zone,and the rebound range of the roof and floor.Within the plastic zone of coal,the energy released per unit volume of coal and the induced kinetic energy exhibit a nonlinear increase with mining depth and stress concentration factor,while they decrease linearly as the width of the plastic zone increases.Similarly,the driving energy per unit volume of the roof and floor shows a nonlinear increase with mining depth and stress concentration factor,a linear increase with the rebound range of the roof and floor,and a linear decrease with the width of the plastic zone.A rock burst risk evaluation method is developed based on the kinetic energy model.Field observations demonstrate that this method aligns with the drilling cuttings rock burst risk assessment method,thereby confirming its validity.展开更多
Meteor Burst Communication(MBC),a niche yet revolutionary wireless communication paradigm,exploits the transient ionized trails generated by meteors ablating in Earth’s atmosphere to enable sporadic yet resilient lon...Meteor Burst Communication(MBC),a niche yet revolutionary wireless communication paradigm,exploits the transient ionized trails generated by meteors ablating in Earth’s atmosphere to enable sporadic yet resilient long-distance radio links.Known for its exceptional resilience,robustness,and sustained connectivity,MBC holds significant promise for applications in emergency communications,remote area connectivity,military/defense systems,and environmental monitoring.However,the scientific exploration and application of MBC have long been highly challenging.In particular,under the combined influence of multiple physical field factors,the channel experiences superimposed multiple random fading effects,exhibiting bursty,highly time-varying,and strongly random characteristics.This persistent technical challenge has resulted in the absence of a practical statistical channel model for MBC to date.展开更多
To evaluate the accuracy of rockburst tendency classification in coal-bearing sandstone strata,this study conducted uniaxial compression loading and unloading tests on sandstone samples with four distinct grain sizes....To evaluate the accuracy of rockburst tendency classification in coal-bearing sandstone strata,this study conducted uniaxial compression loading and unloading tests on sandstone samples with four distinct grain sizes.The tests involved loading the samples to 60%,70%,and 80%of their uniaxial compressive strength,followed by unloading and reloading until failure.Key parameters such as the elastic energy index and linear elasticity criteria were derived from these tests.Additionally,rock fragments were collected to calculate their initial ejection kinetic energy,serving as a measure of rockburst tendency.The classification of rockburst tendency was conducted using grading methods based on burst energy index(WET),pre-peak stored elastic energy(PES)and experimental observations.Multi-class classification and regression analyses were applied to machine learning models using experimental data to predict rockburst tendency levels.A comparative analysis of models from two libraries revealed that the Random Forest model achieved the highest accuracy in classification,while the Ada Boost Regressor model excelled in regression predictions.This study highlights that on a laboratory scale,integrating ejection kinetic energy with the unloading ratio,failure load,W_(ET)and PES through machine learning offers a highly accurate and reliable approach for determining rockburst tendency levels.展开更多
An imbalance in adenosine-mediated signaling,particularly the increased A_(2A)R-mediated signaling,plays a role in the pathogenesis of Parkinson's disease.Existing therapeutic approaches fail to alter disease prog...An imbalance in adenosine-mediated signaling,particularly the increased A_(2A)R-mediated signaling,plays a role in the pathogenesis of Parkinson's disease.Existing therapeutic approaches fail to alter disease progression,demonstrating the need for novel approaches in PD.Repetitive transcranial magnetic stimulation is a non-invasive approach that has been shown to improve motor and non-motor symptoms of Parkinson's disease.However,the underlying mechanisms of the beneficial effects of repetitive transcranial magnetic stimulation remain unknown.The purpose of this study is to investigate the extent to which the beneficial effects of prolonged intermittent theta burst stimulation in the 6-hydroxydopamine model of experimental parkinsonism are based on modulation of adenosine-mediated signaling.Animals with unilateral 6-hydroxydopamine lesions underwent intermittent theta burst stimulation for 3 weeks and were tested for motor skills using the Rotarod test.Immunoblot,quantitative reverse transcription polymerase chain reaction,immunohistochemistry,and biochemical analysis of components of adenosine-mediated signaling were performed on the synaptosomal fraction of the lesioned caudate putamen.Prolonged intermittent theta burst stimulation improved motor symptoms in 6-hydroxydopamine-lesioned animals.A 6-hydroxydopamine lesion resulted in progressive loss of dopaminergic neurons in the caudate putamen.Treatment with intermittent theta burst stimulation began 7 days after the lesion,coinciding with the onset of motor symptoms.After treatment with prolonged intermittent theta burst stimulation,complete motor recovery was observed.This improvement was accompanied by downregulation of the e N/CD73-A_(2A)R pathway and a return to physiological levels of A_(1)R-adenosine deaminase 1 after 3 weeks of intermittent theta burst stimulation.Our results demonstrated that 6-hydroxydopamine-induced degeneration reduced the expression of A_(1)R and elevated the expression of A_(2A)R.Intermittent theta burst stimulation reversed these effects by restoring the abundances of A_(1)R and A_(2A)R to control levels.The shift in ARs expression likely restored the balance between dopamine-adenosine signaling,ultimately leading to the recovery of motor control.展开更多
A numerical method to predict the bursting strength of filament wound composite rocket motor case is proposed here.This method can evaluate the longitudinal stress evolution of each composite layer as impregnated fila...A numerical method to predict the bursting strength of filament wound composite rocket motor case is proposed here.This method can evaluate the longitudinal stress evolution of each composite layer as impregnated filaments with fiber tension are wound layer by layer,and consider the effects of accumulated stress and deformation during filament winding on the bursting strength of composite case.Taking∅520 mm composite cases as a case study,the filament-winding-process-induced stress and deformation as well as progressive damage behavior are numerically predicted,followed by a comparison with experimental results.The numerical results show that the predicted bursting pressures for composite cases manufactured on the mandrels with and without a flexible component are 14.20 MPa and 21.40 MPa,respectively.These values exhibit slight deviation from the measured pressures of 13.50 MPa and 21.57 MPa.Moreover,the predicted damage locations,situated respectively in the dome and cylinder,agree well with the experimental observation.These observations indicate that use of flexible component reduces the load-bearing capacity of the domes.Furthermore,it validates the reliability and accuracy of the proposed numerical method in predicting the bursting strength of composite cases.展开更多
Sterile neutrinos can influence the evolution of the Universe,and thus cosmological observations can be used to detect them.Future gravitational-wave(GW)observations can precisely measure absolute cosmological distanc...Sterile neutrinos can influence the evolution of the Universe,and thus cosmological observations can be used to detect them.Future gravitational-wave(GW)observations can precisely measure absolute cosmological distances,helping to break parameter degeneracies generated by traditional cosmological observations.This advancement can lead to much tighter constraints on sterile neutrino parameters.This work provides a preliminary forecast for detecting sterile neutrinos using third-generation GW detectors in combination with future shortγ-ray burst observations from a THESEUS-like telescope,an approach not previously explored in the literature.Both massless and massive sterile neutrinos are considered within theΛCDM cosmology.We find that using GW data can greatly enhance the detection capability for massless sterile neutrinos,reaching 3σlevel.For massive sterile neutrinos,GW data can also greatly assist in improving the parameter constraints,but it seems that effective detection is still not feasible.展开更多
Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under norm...Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under normal temperature and pressure environments are commonly employed;however,in certain configurations,such as at high-altitudes(HAs),the environment may involve low temperature and pressure conditions.The present study develops a theoretical prediction model for the TP path under reduced pressure and temperature conditions,utilizing the image bursts method,reflected polar analysis,and dimensional analysis.The model's accuracy is evaluated through numerical simulations and experimental data.Results indicate that the prediction model effectively evaluates the TP path under diminished temperature and pressure conditions,with most predictions falling within a±15%deviation.It was found that the TP height increases with altitude.As the altitude rises from 0 m to 10,000 m,the average TP height increases by 61.7%,87.9%,109.0%,and 134.3%for the scaled height of burst of 1.5 m,2.0 m,2.5 m,and 3.0 m,respectively.Moreover,the variation in TP height under HA environments closely mirrors that observed under corresponding reduced pressure conditions.In HA environments,only the effect of low-pressure conditions on the TP path needs to be considered,as the environmental lowtemperature has a minimal effect.展开更多
The effects and rules of the dimensionless parameterξon neutrino annihilation v+v→e^(-)+e^(+)dominated gamma-ray bursts are analysed and investigated within the context of black holes in asymptotic safety.We also co...The effects and rules of the dimensionless parameterξon neutrino annihilation v+v→e^(-)+e^(+)dominated gamma-ray bursts are analysed and investigated within the context of black holes in asymptotic safety.We also computationally model photon orbits around black holes,as photons and neutrinos have the same geodesic equations near black holes.We show that the black hole shadow radius decreases with increasingξ.Calculations are made to determine the temperature of the accretion disk surrounding the black hole and the ratio Q/Q_(Newt)of energy deposition per unit time and compared to that of the Newtonian scenario.The accretion disk temperature peaks at a higher temperature due to quantum gravity corrections,which increases the probability of neutrino emission from the black hole.It is interesting to note that larger quantum gravity effects cause the ratio value to significantly decline.In the neutrinoantineutrino annihilation process,the energy deposition rate is sufficient even while the energy conversion is inhibited because of quantum corrections.Gamma-ray bursts might originate from the corrected annihilation process.Additionally,we examine the derivative dQ/dr about the star radius r.The findings demonstrate that the ratio is lowered by the black hole's quantum influence.The neutrino pair annihilation grows weaker the more prominent the influence of quantum gravity.展开更多
To the editor:A wide range of affective disorders affects people of all ages globally and contributes significantly to the global disease burden.1 In China,a nationwide survey found a 3.21% prevalence of affective dis...To the editor:A wide range of affective disorders affects people of all ages globally and contributes significantly to the global disease burden.1 In China,a nationwide survey found a 3.21% prevalence of affective disorders in children and adolescents,with major depressive disorder(MDD)at 2.00%and bipolar disorder at 0.86%.展开更多
This paper addresses the performance degradation issue in a fast radio burst search pipeline based on deep learning.This issue is caused by the class imbalance of the radio frequency interference samples in the traini...This paper addresses the performance degradation issue in a fast radio burst search pipeline based on deep learning.This issue is caused by the class imbalance of the radio frequency interference samples in the training dataset,and one solution is applied to improve the distribution of the training data by augmenting minority class samples using a deep convolutional generative adversarial network.Experi.mental results demonstrate that retraining the deep learning model with the newly generated dataset leads to a new fast radio burst classifier,which effectively reduces false positives caused by periodic wide-band impulsive radio frequency interference,thereby enhancing the performance of the search pipeline.展开更多
This study focuses on steeply inclined and extremely thick coal seams(SIETCS)characterized by immense thickness,a steep inclination of coal seams(87°),and high horizontal stress.The geological conditions and mini...This study focuses on steeply inclined and extremely thick coal seams(SIETCS)characterized by immense thickness,a steep inclination of coal seams(87°),and high horizontal stress.The geological conditions and mining technology associated with SIETCS differ significantly from those of generally inclined coal seams,resulting in notable variations in roadway stress distributions.On SIETCS have predominantly examined the impact of rock layers flanking coal seams on rock bursts,with limited emphasis on SIETCS roadways.This study employs comprehensive methods,integrating numerical simulations,theoretical analyses,and field detections to investigate the stress distribution of SIETCS and the mechanisms of rock burst-induced vertical damage,subsequently validated in situ.The vertical stress in SIETCS is minimal,while horizontal stress is concentrated,leading to the formation of layered crack structures(LCS)that distribute above and below the roadways.Additionally,elastic energy significantly concentrates within the LCS.Axial dynamic compressive stress and vertical dynamic tensile stress along the LCS diminish its stability,readily triggering failure.During the LCS failure process,the stored energy is released,converting into kinetic energy required for coal body ejection after reaching the minimum energy for failure and dissipative energy,ultimately leading to rock burst-induced vertical damage in roadways.On-site detection and analysis within SIETCS,along with historical rock burst data,confirm the existence of LCS and its role in inducing vertical rock burst damage.This research establishes essential foundations for preventing rock bursts within SIETCS.展开更多
Recently,the NGPON2 standards organization has decided to deploy LDPC code in upstream and downstream channels in next-generation Ethernet passive optical network(NG-EPON)systems.However,PON upstream channels operate ...Recently,the NGPON2 standards organization has decided to deploy LDPC code in upstream and downstream channels in next-generation Ethernet passive optical network(NG-EPON)systems.However,PON upstream channels operate in burst-mode,hence the turn-on effects in optical network units(ONUs)may introduce burst errors,which are difficult for LDPC to deal with.One of the solutions is introducing an interleaver to convert consecutive burst errors into separate random errors.The traditional interleavers such as the block interleaver and the random interleaver,only consider dispersing the consecutive errors.In this paper,we present a design methodology for channel-adaptive interleaving pattern by joint optimizing of interleaving and LDPC decoding in PON systems deploying LDPC codes.After determining the interleaving pattern where the bits can be recovered with more reliable messages during LDPC iterative decoding,we map the bits from the potential locations of burst errors to the interleaving positions.By doing so,we can not only disperse the burst errors but also make full use of the LDPC code to improve its decoding performance.The numerical results show that the proposed interleaving scheme has a better performance under any burst-error length.展开更多
The increasingly severe state of coal burst disaster has emerged as a critical factor constraining coal mine safety production,and it has become a challenging task to enhance the accuracy of coal burst disaster predic...The increasingly severe state of coal burst disaster has emerged as a critical factor constraining coal mine safety production,and it has become a challenging task to enhance the accuracy of coal burst disaster prediction.To address the issue of insufficient exploration of the spatio-temporal characteristic of microseismic data and the challenging selection of the optimal time window size in spatio-temporal prediction,this paper integrates deep learning methods and theory to propose a novel coal burst spatio-temporal prediction method based on Bidirectional Long Short-Term Memory(Bi-LSTM)network.The method involves three main modules,including microseismic spatio-temporal characteristic indicators construction,temporal prediction model,and spatial prediction model.To validate the effectiveness of the proposed method,engineering application tests are conducted at a high-risk working face in the Ordos mining area of Inner Mongolia,focusing on 13 high-energy microseismic events with energy levels greater than 105 J.In terms of temporal prediction,the analysis indicates that the temporal prediction results consist of 10 strong predictions and 3 medium predictions,and there is no false alarm detected throughout the entire testing period.Moreover,compared to the traditional threshold-based coal burst temporal prediction method,the accuracy of the proposed method is increased by 38.5%.In terms of spatial prediction,the distribution of spatial prediction results for high-energy events comprises 6 strong hazard predictions,3 medium hazard predictions,and 4 weak hazard predictions.展开更多
We conducted an analysis of the continuum during the onset and initial decline phases of the 2023 outburst in transient neutron star low-mass X-ray binary Aql X–1 using broadband observations from the Hard X-ray Modu...We conducted an analysis of the continuum during the onset and initial decline phases of the 2023 outburst in transient neutron star low-mass X-ray binary Aql X–1 using broadband observations from the Hard X-ray Modulation Telescope(Insight-HXMT)instrument.To determine the most appropriate model for the continuum of this outburst,we employed three models to explore the evolution of the spectral component.These observations revealed that the source transitions from the hard state to the soft state.The disk-corona and sphere-corona models both adequately described the spectra of the hard state,while the double blackbody model became preferable after the hard X-ray emission(>25 keV)disappeared during the state transition.In the soft state,the total emission is dominated by the accretion disk and two blackbody components.The combination of the sphere-corona model and the double blackbody model is the most suitable model for this outburst.The results suggest that as the source transitioned into the soft state,the emission from the boundary layer was enhanced,and a hot spot occurred.Notably,we identified two type-ⅠX-ray bursts,one of which exhibited a significant hard X-ray deficit(significance~4.82σ),which indicates that Insight-HXMT has the capability to capture the evolution of the corona in a single burst.展开更多
The study of high-energy gamma-ray emission from gamma-ray bursts(GRBs)involves complex synchrotron radiation and synchrotron self-Compton(SSC)scattering mechanisms with multiple parameters exhibiting a wide distribut...The study of high-energy gamma-ray emission from gamma-ray bursts(GRBs)involves complex synchrotron radiation and synchrotron self-Compton(SSC)scattering mechanisms with multiple parameters exhibiting a wide distribution.Recent advancements in GRB research,particularly the observation of very high energy(VHE,>100 Ge V)radiation,have ushered in a new era of multiwavelength exploration,offering fresh perspectives and limitations for understanding GRB radiation mechanisms.This study aimed to leverage VHE observations to refine constraints on synchrotron+SSC radiation from electrons accelerated by forward shocks.By analyzing two external environments—the uniform interstellar medium and stratified stellar wind medium,we conducted spectral and variability fitting for five specific bursts(GRB 180720B,GRB 190114C,GRB 190829A,GRB 201216C,and GRB 221009A)to identify the optimal parameters characterizing these events.A comparative analysis of model parameter distributions with and without VHE radiation observations reveals that the magnetic energy equipartition factorεBis more concentrated with VHE emissions.This suggests that VHE emissions may offer greater constraints on this microphysical parameter.Additionally,we found that the energy budget between VHE and ke V–Me Vγ-ray emissions under the SSC radiation exhibits an almost linear relationship,which may serve as a tool to differentiate radiation mechanisms.We anticipate future statistical analyses of additional VHE bursts to validate our findings.展开更多
Serving as the initiating explosive devices between the propellant tank and the engines,metal-based rupture diaphragms are widely used in ramjet igniters owing to the advantages provided by their simple structure,smal...Serving as the initiating explosive devices between the propellant tank and the engines,metal-based rupture diaphragms are widely used in ramjet igniters owing to the advantages provided by their simple structure,small size,and low cost.However,the reliability of rupture pressure directly affects the success of engine ignition and rocket launch,which is mainly influenced by factors like material,structure,and residual thickness of the surface notch of the diaphragm.Among those,the geometry of the notch is easy to define and control when compared to the mechanical parameters of the ruptured diaphragm.Thus,to make the diaphragm rupture(1A30 Al)within the required pressure range(0.4 MPa±3.5%)with highly sensitive and reliability,we draw inspiration from the arthropod’s force-sensitive slit organ which encompasses curved microgrooves to design a Ω-shaped notch for the rupture diaphragm.Finite element analysis is used to study the relationship between the burst pressure and geometric dimension of theΩ-shaped and bioinspired microgroove.Based on that,metal-based rupture diaphragms are fabricated by femtosecond laser processing technology,followed by rupture tests.Experiment results demonstrate that the practical rupture pressure of the diaphragm is highly consistent with the finite element analysis results,which verifies the effectiveness of the bionic design.展开更多
Solar radio burst(SRB)is one of the main natural interference sources of Global Positioning System(GPS)signals and can reduce the signal-to-noise ratio(SNR),directly affecting the tracking performance of GPS receivers...Solar radio burst(SRB)is one of the main natural interference sources of Global Positioning System(GPS)signals and can reduce the signal-to-noise ratio(SNR),directly affecting the tracking performance of GPS receivers.In this paper,a tracking algorithm based on the adaptive Kalman filter(AKF)with carrier-to-noise ratio estimation is proposed and compared with the conventional second-order phase-locked loop tracking algo-rithms and the improved Sage-Husa adaptive Kalman filter(SHAKF)algorithm.It is discovered that when the SRBs occur,the improved SHAKF and the AKF with carrier-to-noise ratio estimation enable stable tracking to loop signals.The conven-tional second-order phase-locked loop tracking algorithms fail to track the receiver signal.The standard deviation of the carrier phase error of the AKF with carrier-to-noise ratio estimation out-performs 50.51%of the improved SHAKF algorithm,showing less fluctuation and better stability.The proposed algorithm is proven to show more excellent adaptability in the severe envi-ronment caused by the SRB occurrence and has better tracking performance.展开更多
El Ni?o–Southern Oscillation(ENSO) is an oscillation of the ocean–atmosphere system in the tropical Pacific, which is argued to be energized by high-frequency stochastic atmospheric disturbances. Among these disturb...El Ni?o–Southern Oscillation(ENSO) is an oscillation of the ocean–atmosphere system in the tropical Pacific, which is argued to be energized by high-frequency stochastic atmospheric disturbances. Among these disturbances, westerly wind bursts(WWBs) play a crucial role in the development of El Ni?o by generating eastward-propagating downwelling Kelvin waves and suppressing the thermocline in the central-eastern equatorial Pacific. The present work elucidates distinct seasonal evolutions of WWBs during cyclic and noncyclic El Ni?o events, and their association with the local sea surface temperature anomalies(SSTAs). For noncyclic El Ni?o events, WWBs prevail over the western-central equatorial Pacific during spring of the developing year, accompanied by local warming SSTAs. In contrast, active WWBs cannot be observed until the developing summer for cyclic El Ni?o events. Significant differences in high-frequency WWBs and associated local deep convection appear in the developing spring season of noncyclic and cyclic El Ni?o events. These differences are closely linked to local SSTAs in the western-central equatorial Pacific via the stimulation of atmospheric deep convection,preceding the full manifestation of ENSO-associated large-scale SSTAs in the central-eastern tropical Pacific. The observed difference in WWBs for noncyclic and cyclic El Ni?o events and its association with the western-central equatorial Pacific SSTAs is realistically reproduced in a coupled general circulation model. This study enhances our comprehension of El Ni?o development by illustrating the intricate connection between WWBs and El Ni?o evolution from the ENSO cycle perspective.展开更多
The natural property of rock material,whether impact occurs,is the key influencing factor of the occurrence of rock burst disaster.To accurately assess rock burst proneness,this study focuses on typical sandstone as t...The natural property of rock material,whether impact occurs,is the key influencing factor of the occurrence of rock burst disaster.To accurately assess rock burst proneness,this study focuses on typical sandstone as the research object.Uniaxial cyclic loading and unloading tests were conducted to measure the elastic strain energy accumulated in sandstone under different stress levels and a relationship between elastic strain energy and stress level was established.The results show that:(1)The peak stress under cyclic loading and unloading conditions is slightly lower than the uniaxial compressive strength.With an increase in the number of cycles,the internal damage of sandstone continues to accumulate,and the mechanical properties such as compressive strength continue to deteriorate;(2)With an increase in stress,the input strain energy,elastic strain energy,and dissipated strain energy also increase;(3)When the stress is low,the increase in elastic strain energy is large and shows a steady growth;with an increase in stress,the increase of elastic strain energy decreases;(4)The square of stress at any time has a good linear relationship with elastic strain energy.According to the relationship obtained from the test,the elastic strain energy at the peak stress time can be obtained;(5)A new criterion for assessing rock burst proneness is proposed:residual energy release rate index W_(T),which characterizes the energy release per unit time when the rock burst occurs.The intervals for evaluating the rock burst proneness of the residual energy release rate index W_(T) are as follows:W_(T)<0.025,indicating no rock burst proneness;0.025≤W_(T)<0.15,indicating weak rock burst proneness;0.15≤W_(T)<2,indicating medium rock burst proneness;W_(T)>2,indicating strong rock burst proneness;and(6)The rationality of the proposed residual energy release rate index W_(T) is verified by the multi-index method and the multi-sample method,and the proposed residual energy release rate index is used to determine the rock burst proneness of 10 kinds of rock samples.The evaluation accuracy is shown to be high,and it can reflect the actual rock burst proneness.展开更多
In order to study the mechanics,acoustic emission(AE)and electromagnetic emission(EME)response law of bursting liability coal at different loading rates,uniaxial compression tests were carried out on coal mass from Ko...In order to study the mechanics,acoustic emission(AE)and electromagnetic emission(EME)response law of bursting liability coal at different loading rates,uniaxial compression tests were carried out on coal mass from Konggu Coal Mine.The corresponding relations among mechanical properties,AE and EME signals in the process of coal failure under loading were analyzed,and the energy evolution law of coal failure with bursting liability under loading rate was discussed.The results show that within a certain range of loading rate,the higher the loading rate,the higher the compressive strength and peak load of bursting liability coal,and the shorter the time for coal to reach the peak load.Under different loading rates,the mechanics,AE and EME signals of coal samples can be well corresponded.When the loading rate is low,the number of blocks destroyed of coal sample is large and the block size is relatively small,and the blocks are mainly scattered around the test platform.When the loading rate is high,the number of damaged blocks is relatively small and the block size is relatively large,and the blocks are far away from the test bench.When loading at a low rate,the internal cracks in coal can be fully developed and connected,and the energy release rate is relatively uniform in the process of loading and failure of coal sample.In the case of high loading rate,the energy release rate of coal sample in the loading process is much smaller than that in the moment of failure.Combining the above test results with the actual situation of the working face,it can be concluded that the total energy stored in the coal of fast mining increases and the threshold of impact decreases compared with that of slow mining.Therefore,under the disturbance of external dynamic load,rapid mining is more likely to induce rock burst.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52374094 and 52274086)the Climbling Project of Taishan Scholar in Shandong Province(No.tspd20210313)the Shandong Provincial Youth Innovation and Technology Support Program(No.2024KJH069)。
文摘The accumulation and release of deformation energy within the rock mass of a roadway are primary contributors to the occurrence of rock bursts.This study introduces a calculation model for the kinetic energy generated during roadway excavation,which is based on the fracture and energy states of the rock mass.The relationships among the mining depth,width of the plastic zone,rebound range of the roof and floor,stress concentration factor,and the induced kinetic energy are systematically explored.Furthermore,a rock burst risk evaluation method is proposed.The findings indicate that the energy evolution of the rock mass can be categorized into four stages:energy accumulation due to in-situ stress,energy accumulation resulting from coal compression,energy dissipation through coal plastic deformation,and energy consumption due to coal failure.The energy release from the rock mass is influenced by several factors,including mining depth,stress concentration factor,the width of the plastic zone,and the rebound range of the roof and floor.Within the plastic zone of coal,the energy released per unit volume of coal and the induced kinetic energy exhibit a nonlinear increase with mining depth and stress concentration factor,while they decrease linearly as the width of the plastic zone increases.Similarly,the driving energy per unit volume of the roof and floor shows a nonlinear increase with mining depth and stress concentration factor,a linear increase with the rebound range of the roof and floor,and a linear decrease with the width of the plastic zone.A rock burst risk evaluation method is developed based on the kinetic energy model.Field observations demonstrate that this method aligns with the drilling cuttings rock burst risk assessment method,thereby confirming its validity.
文摘Meteor Burst Communication(MBC),a niche yet revolutionary wireless communication paradigm,exploits the transient ionized trails generated by meteors ablating in Earth’s atmosphere to enable sporadic yet resilient long-distance radio links.Known for its exceptional resilience,robustness,and sustained connectivity,MBC holds significant promise for applications in emergency communications,remote area connectivity,military/defense systems,and environmental monitoring.However,the scientific exploration and application of MBC have long been highly challenging.In particular,under the combined influence of multiple physical field factors,the channel experiences superimposed multiple random fading effects,exhibiting bursty,highly time-varying,and strongly random characteristics.This persistent technical challenge has resulted in the absence of a practical statistical channel model for MBC to date.
基金financial support for this work provided by the National Natural Science Foundation of China (No.52227901)。
文摘To evaluate the accuracy of rockburst tendency classification in coal-bearing sandstone strata,this study conducted uniaxial compression loading and unloading tests on sandstone samples with four distinct grain sizes.The tests involved loading the samples to 60%,70%,and 80%of their uniaxial compressive strength,followed by unloading and reloading until failure.Key parameters such as the elastic energy index and linear elasticity criteria were derived from these tests.Additionally,rock fragments were collected to calculate their initial ejection kinetic energy,serving as a measure of rockburst tendency.The classification of rockburst tendency was conducted using grading methods based on burst energy index(WET),pre-peak stored elastic energy(PES)and experimental observations.Multi-class classification and regression analyses were applied to machine learning models using experimental data to predict rockburst tendency levels.A comparative analysis of models from two libraries revealed that the Random Forest model achieved the highest accuracy in classification,while the Ada Boost Regressor model excelled in regression predictions.This study highlights that on a laboratory scale,integrating ejection kinetic energy with the unloading ratio,failure load,W_(ET)and PES through machine learning offers a highly accurate and reliable approach for determining rockburst tendency levels.
基金supported by a grant from Ministry of Science,Technological Development and Innovation,Serbia,No.451-03-68/2022-14/200178(to NN)University of Defence,No.MFVMA/02/22-24(to MN)。
文摘An imbalance in adenosine-mediated signaling,particularly the increased A_(2A)R-mediated signaling,plays a role in the pathogenesis of Parkinson's disease.Existing therapeutic approaches fail to alter disease progression,demonstrating the need for novel approaches in PD.Repetitive transcranial magnetic stimulation is a non-invasive approach that has been shown to improve motor and non-motor symptoms of Parkinson's disease.However,the underlying mechanisms of the beneficial effects of repetitive transcranial magnetic stimulation remain unknown.The purpose of this study is to investigate the extent to which the beneficial effects of prolonged intermittent theta burst stimulation in the 6-hydroxydopamine model of experimental parkinsonism are based on modulation of adenosine-mediated signaling.Animals with unilateral 6-hydroxydopamine lesions underwent intermittent theta burst stimulation for 3 weeks and were tested for motor skills using the Rotarod test.Immunoblot,quantitative reverse transcription polymerase chain reaction,immunohistochemistry,and biochemical analysis of components of adenosine-mediated signaling were performed on the synaptosomal fraction of the lesioned caudate putamen.Prolonged intermittent theta burst stimulation improved motor symptoms in 6-hydroxydopamine-lesioned animals.A 6-hydroxydopamine lesion resulted in progressive loss of dopaminergic neurons in the caudate putamen.Treatment with intermittent theta burst stimulation began 7 days after the lesion,coinciding with the onset of motor symptoms.After treatment with prolonged intermittent theta burst stimulation,complete motor recovery was observed.This improvement was accompanied by downregulation of the e N/CD73-A_(2A)R pathway and a return to physiological levels of A_(1)R-adenosine deaminase 1 after 3 weeks of intermittent theta burst stimulation.Our results demonstrated that 6-hydroxydopamine-induced degeneration reduced the expression of A_(1)R and elevated the expression of A_(2A)R.Intermittent theta burst stimulation reversed these effects by restoring the abundances of A_(1)R and A_(2A)R to control levels.The shift in ARs expression likely restored the balance between dopamine-adenosine signaling,ultimately leading to the recovery of motor control.
基金supported by the National Natural Science Foundation of China(No.11902231)the Major Program(JD)of Hubei Province,China(No.2023BAA004).
文摘A numerical method to predict the bursting strength of filament wound composite rocket motor case is proposed here.This method can evaluate the longitudinal stress evolution of each composite layer as impregnated filaments with fiber tension are wound layer by layer,and consider the effects of accumulated stress and deformation during filament winding on the bursting strength of composite case.Taking∅520 mm composite cases as a case study,the filament-winding-process-induced stress and deformation as well as progressive damage behavior are numerically predicted,followed by a comparison with experimental results.The numerical results show that the predicted bursting pressures for composite cases manufactured on the mandrels with and without a flexible component are 14.20 MPa and 21.40 MPa,respectively.These values exhibit slight deviation from the measured pressures of 13.50 MPa and 21.57 MPa.Moreover,the predicted damage locations,situated respectively in the dome and cylinder,agree well with the experimental observation.These observations indicate that use of flexible component reduces the load-bearing capacity of the domes.Furthermore,it validates the reliability and accuracy of the proposed numerical method in predicting the bursting strength of composite cases.
基金supported by the National Natural Science Foundation of China under Grant Nos.12305069,11947022,12473001,11975072,11875102,and 11835009the National SKA Program of China under Grants Nos.2022SKA0110200 and 2022SKA0110203+1 种基金the Program of the Education Department of Liaoning Province under Grant No.JYTMS20231695the National 111 Project under Grant No.B16009。
文摘Sterile neutrinos can influence the evolution of the Universe,and thus cosmological observations can be used to detect them.Future gravitational-wave(GW)observations can precisely measure absolute cosmological distances,helping to break parameter degeneracies generated by traditional cosmological observations.This advancement can lead to much tighter constraints on sterile neutrino parameters.This work provides a preliminary forecast for detecting sterile neutrinos using third-generation GW detectors in combination with future shortγ-ray burst observations from a THESEUS-like telescope,an approach not previously explored in the literature.Both massless and massive sterile neutrinos are considered within theΛCDM cosmology.We find that using GW data can greatly enhance the detection capability for massless sterile neutrinos,reaching 3σlevel.For massive sterile neutrinos,GW data can also greatly assist in improving the parameter constraints,but it seems that effective detection is still not feasible.
基金funding from Anhui Engineering Laboratory of Explosive Materials and Technology Foundation(No.AHBP2022B-04)Natural Science Research Project of Anhui Educational Committee(No.2023AH051221)+1 种基金Anhui Provincial Natural Science Foundation(No.2208085QA26)Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology for the project related to this work.
文摘Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under normal temperature and pressure environments are commonly employed;however,in certain configurations,such as at high-altitudes(HAs),the environment may involve low temperature and pressure conditions.The present study develops a theoretical prediction model for the TP path under reduced pressure and temperature conditions,utilizing the image bursts method,reflected polar analysis,and dimensional analysis.The model's accuracy is evaluated through numerical simulations and experimental data.Results indicate that the prediction model effectively evaluates the TP path under diminished temperature and pressure conditions,with most predictions falling within a±15%deviation.It was found that the TP height increases with altitude.As the altitude rises from 0 m to 10,000 m,the average TP height increases by 61.7%,87.9%,109.0%,and 134.3%for the scaled height of burst of 1.5 m,2.0 m,2.5 m,and 3.0 m,respectively.Moreover,the variation in TP height under HA environments closely mirrors that observed under corresponding reduced pressure conditions.In HA environments,only the effect of low-pressure conditions on the TP path needs to be considered,as the environmental lowtemperature has a minimal effect.
基金partly supported by the Shanghai Key Laboratory of Astrophysics 18DZ2271600。
文摘The effects and rules of the dimensionless parameterξon neutrino annihilation v+v→e^(-)+e^(+)dominated gamma-ray bursts are analysed and investigated within the context of black holes in asymptotic safety.We also computationally model photon orbits around black holes,as photons and neutrinos have the same geodesic equations near black holes.We show that the black hole shadow radius decreases with increasingξ.Calculations are made to determine the temperature of the accretion disk surrounding the black hole and the ratio Q/Q_(Newt)of energy deposition per unit time and compared to that of the Newtonian scenario.The accretion disk temperature peaks at a higher temperature due to quantum gravity corrections,which increases the probability of neutrino emission from the black hole.It is interesting to note that larger quantum gravity effects cause the ratio value to significantly decline.In the neutrinoantineutrino annihilation process,the energy deposition rate is sufficient even while the energy conversion is inhibited because of quantum corrections.Gamma-ray bursts might originate from the corrected annihilation process.Additionally,we examine the derivative dQ/dr about the star radius r.The findings demonstrate that the ratio is lowered by the black hole's quantum influence.The neutrino pair annihilation grows weaker the more prominent the influence of quantum gravity.
基金the Tianjin Health Research Project(Grant No.TJWJ2023MS038)Tianjin Education Commission Research Project(Grant No.2023KJ044)S&T Program of Hebei(SG2021189)。
文摘To the editor:A wide range of affective disorders affects people of all ages globally and contributes significantly to the global disease burden.1 In China,a nationwide survey found a 3.21% prevalence of affective disorders in children and adolescents,with major depressive disorder(MDD)at 2.00%and bipolar disorder at 0.86%.
基金supported by the Chinese Academy of Science"Light of West China"Program(2022-XBQNXZ-015)the National Natural Science Foundation of China(11903071)the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China and administered by the Chinese Academy of Sciences。
文摘This paper addresses the performance degradation issue in a fast radio burst search pipeline based on deep learning.This issue is caused by the class imbalance of the radio frequency interference samples in the training dataset,and one solution is applied to improve the distribution of the training data by augmenting minority class samples using a deep convolutional generative adversarial network.Experi.mental results demonstrate that retraining the deep learning model with the newly generated dataset leads to a new fast radio burst classifier,which effectively reduces false positives caused by periodic wide-band impulsive radio frequency interference,thereby enhancing the performance of the search pipeline.
基金support of the National Natural Science Foundation of China(52374180,52327804).
文摘This study focuses on steeply inclined and extremely thick coal seams(SIETCS)characterized by immense thickness,a steep inclination of coal seams(87°),and high horizontal stress.The geological conditions and mining technology associated with SIETCS differ significantly from those of generally inclined coal seams,resulting in notable variations in roadway stress distributions.On SIETCS have predominantly examined the impact of rock layers flanking coal seams on rock bursts,with limited emphasis on SIETCS roadways.This study employs comprehensive methods,integrating numerical simulations,theoretical analyses,and field detections to investigate the stress distribution of SIETCS and the mechanisms of rock burst-induced vertical damage,subsequently validated in situ.The vertical stress in SIETCS is minimal,while horizontal stress is concentrated,leading to the formation of layered crack structures(LCS)that distribute above and below the roadways.Additionally,elastic energy significantly concentrates within the LCS.Axial dynamic compressive stress and vertical dynamic tensile stress along the LCS diminish its stability,readily triggering failure.During the LCS failure process,the stored energy is released,converting into kinetic energy required for coal body ejection after reaching the minimum energy for failure and dissipative energy,ultimately leading to rock burst-induced vertical damage in roadways.On-site detection and analysis within SIETCS,along with historical rock burst data,confirm the existence of LCS and its role in inducing vertical rock burst damage.This research establishes essential foundations for preventing rock bursts within SIETCS.
基金supported by National Natural Science Foundation of China(No.U21A20454).
文摘Recently,the NGPON2 standards organization has decided to deploy LDPC code in upstream and downstream channels in next-generation Ethernet passive optical network(NG-EPON)systems.However,PON upstream channels operate in burst-mode,hence the turn-on effects in optical network units(ONUs)may introduce burst errors,which are difficult for LDPC to deal with.One of the solutions is introducing an interleaver to convert consecutive burst errors into separate random errors.The traditional interleavers such as the block interleaver and the random interleaver,only consider dispersing the consecutive errors.In this paper,we present a design methodology for channel-adaptive interleaving pattern by joint optimizing of interleaving and LDPC decoding in PON systems deploying LDPC codes.After determining the interleaving pattern where the bits can be recovered with more reliable messages during LDPC iterative decoding,we map the bits from the potential locations of burst errors to the interleaving positions.By doing so,we can not only disperse the burst errors but also make full use of the LDPC code to improve its decoding performance.The numerical results show that the proposed interleaving scheme has a better performance under any burst-error length.
基金supported by the National Research and Development Program(2022YFC3004603)the Jiangsu Province International Collaboration Program-Key National Industrial Technology Research and Development Cooperation Projects(BZ2023050)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20221109)the National Natural Science Foundation of China(52274098).
文摘The increasingly severe state of coal burst disaster has emerged as a critical factor constraining coal mine safety production,and it has become a challenging task to enhance the accuracy of coal burst disaster prediction.To address the issue of insufficient exploration of the spatio-temporal characteristic of microseismic data and the challenging selection of the optimal time window size in spatio-temporal prediction,this paper integrates deep learning methods and theory to propose a novel coal burst spatio-temporal prediction method based on Bidirectional Long Short-Term Memory(Bi-LSTM)network.The method involves three main modules,including microseismic spatio-temporal characteristic indicators construction,temporal prediction model,and spatial prediction model.To validate the effectiveness of the proposed method,engineering application tests are conducted at a high-risk working face in the Ordos mining area of Inner Mongolia,focusing on 13 high-energy microseismic events with energy levels greater than 105 J.In terms of temporal prediction,the analysis indicates that the temporal prediction results consist of 10 strong predictions and 3 medium predictions,and there is no false alarm detected throughout the entire testing period.Moreover,compared to the traditional threshold-based coal burst temporal prediction method,the accuracy of the proposed method is increased by 38.5%.In terms of spatial prediction,the distribution of spatial prediction results for high-energy events comprises 6 strong hazard predictions,3 medium hazard predictions,and 4 weak hazard predictions.
基金supported by the National Key R&D Program of China(2023YFE0101200)supported by the National Key R&D Program of China(2021YFA0718500)+3 种基金Yunnan Revitalization Talent Support Program(Yun Ling Scholar Award)the National Natural Science Foundation of China(NSFC)grant 12393813the science research grants from the China Manned Space Projectsupported by Hunan Education Department Foundation(grant No.21A0096)。
文摘We conducted an analysis of the continuum during the onset and initial decline phases of the 2023 outburst in transient neutron star low-mass X-ray binary Aql X–1 using broadband observations from the Hard X-ray Modulation Telescope(Insight-HXMT)instrument.To determine the most appropriate model for the continuum of this outburst,we employed three models to explore the evolution of the spectral component.These observations revealed that the source transitions from the hard state to the soft state.The disk-corona and sphere-corona models both adequately described the spectra of the hard state,while the double blackbody model became preferable after the hard X-ray emission(>25 keV)disappeared during the state transition.In the soft state,the total emission is dominated by the accretion disk and two blackbody components.The combination of the sphere-corona model and the double blackbody model is the most suitable model for this outburst.The results suggest that as the source transitioned into the soft state,the emission from the boundary layer was enhanced,and a hot spot occurred.Notably,we identified two type-ⅠX-ray bursts,one of which exhibited a significant hard X-ray deficit(significance~4.82σ),which indicates that Insight-HXMT has the capability to capture the evolution of the corona in a single burst.
基金supported by the National Natural Science Foundation of China(NSFC,grant Nos.12275279 and 12405124)the China Postdoctoral Science Foundation(No.2023M730423)Horizontal research project in natural sciences(No.H20230120)。
文摘The study of high-energy gamma-ray emission from gamma-ray bursts(GRBs)involves complex synchrotron radiation and synchrotron self-Compton(SSC)scattering mechanisms with multiple parameters exhibiting a wide distribution.Recent advancements in GRB research,particularly the observation of very high energy(VHE,>100 Ge V)radiation,have ushered in a new era of multiwavelength exploration,offering fresh perspectives and limitations for understanding GRB radiation mechanisms.This study aimed to leverage VHE observations to refine constraints on synchrotron+SSC radiation from electrons accelerated by forward shocks.By analyzing two external environments—the uniform interstellar medium and stratified stellar wind medium,we conducted spectral and variability fitting for five specific bursts(GRB 180720B,GRB 190114C,GRB 190829A,GRB 201216C,and GRB 221009A)to identify the optimal parameters characterizing these events.A comparative analysis of model parameter distributions with and without VHE radiation observations reveals that the magnetic energy equipartition factorεBis more concentrated with VHE emissions.This suggests that VHE emissions may offer greater constraints on this microphysical parameter.Additionally,we found that the energy budget between VHE and ke V–Me Vγ-ray emissions under the SSC radiation exhibits an almost linear relationship,which may serve as a tool to differentiate radiation mechanisms.We anticipate future statistical analyses of additional VHE bursts to validate our findings.
基金supported by the National Key R&D Program of China(Grant No.2022YFB4601700).
文摘Serving as the initiating explosive devices between the propellant tank and the engines,metal-based rupture diaphragms are widely used in ramjet igniters owing to the advantages provided by their simple structure,small size,and low cost.However,the reliability of rupture pressure directly affects the success of engine ignition and rocket launch,which is mainly influenced by factors like material,structure,and residual thickness of the surface notch of the diaphragm.Among those,the geometry of the notch is easy to define and control when compared to the mechanical parameters of the ruptured diaphragm.Thus,to make the diaphragm rupture(1A30 Al)within the required pressure range(0.4 MPa±3.5%)with highly sensitive and reliability,we draw inspiration from the arthropod’s force-sensitive slit organ which encompasses curved microgrooves to design a Ω-shaped notch for the rupture diaphragm.Finite element analysis is used to study the relationship between the burst pressure and geometric dimension of theΩ-shaped and bioinspired microgroove.Based on that,metal-based rupture diaphragms are fabricated by femtosecond laser processing technology,followed by rupture tests.Experiment results demonstrate that the practical rupture pressure of the diaphragm is highly consistent with the finite element analysis results,which verifies the effectiveness of the bionic design.
基金supported by the Foundation of Key Laboratory of Micro-inertial Instrument and Advanced Navigation Technology,Ministry of Education,Chinathe National Natural Science Foundation of China (61873064)
文摘Solar radio burst(SRB)is one of the main natural interference sources of Global Positioning System(GPS)signals and can reduce the signal-to-noise ratio(SNR),directly affecting the tracking performance of GPS receivers.In this paper,a tracking algorithm based on the adaptive Kalman filter(AKF)with carrier-to-noise ratio estimation is proposed and compared with the conventional second-order phase-locked loop tracking algo-rithms and the improved Sage-Husa adaptive Kalman filter(SHAKF)algorithm.It is discovered that when the SRBs occur,the improved SHAKF and the AKF with carrier-to-noise ratio estimation enable stable tracking to loop signals.The conven-tional second-order phase-locked loop tracking algorithms fail to track the receiver signal.The standard deviation of the carrier phase error of the AKF with carrier-to-noise ratio estimation out-performs 50.51%of the improved SHAKF algorithm,showing less fluctuation and better stability.The proposed algorithm is proven to show more excellent adaptability in the severe envi-ronment caused by the SRB occurrence and has better tracking performance.
基金supported by the National Nature Science Foundation of China (Grant No.42088101)。
文摘El Ni?o–Southern Oscillation(ENSO) is an oscillation of the ocean–atmosphere system in the tropical Pacific, which is argued to be energized by high-frequency stochastic atmospheric disturbances. Among these disturbances, westerly wind bursts(WWBs) play a crucial role in the development of El Ni?o by generating eastward-propagating downwelling Kelvin waves and suppressing the thermocline in the central-eastern equatorial Pacific. The present work elucidates distinct seasonal evolutions of WWBs during cyclic and noncyclic El Ni?o events, and their association with the local sea surface temperature anomalies(SSTAs). For noncyclic El Ni?o events, WWBs prevail over the western-central equatorial Pacific during spring of the developing year, accompanied by local warming SSTAs. In contrast, active WWBs cannot be observed until the developing summer for cyclic El Ni?o events. Significant differences in high-frequency WWBs and associated local deep convection appear in the developing spring season of noncyclic and cyclic El Ni?o events. These differences are closely linked to local SSTAs in the western-central equatorial Pacific via the stimulation of atmospheric deep convection,preceding the full manifestation of ENSO-associated large-scale SSTAs in the central-eastern tropical Pacific. The observed difference in WWBs for noncyclic and cyclic El Ni?o events and its association with the western-central equatorial Pacific SSTAs is realistically reproduced in a coupled general circulation model. This study enhances our comprehension of El Ni?o development by illustrating the intricate connection between WWBs and El Ni?o evolution from the ENSO cycle perspective.
基金supported by the National Natural Science Foundation of China(Grant No.52304142)basic scientific research fees of colleges and universities directly under Inner Mongolia Autonomous Region(Grant No.2023QNJS108).
文摘The natural property of rock material,whether impact occurs,is the key influencing factor of the occurrence of rock burst disaster.To accurately assess rock burst proneness,this study focuses on typical sandstone as the research object.Uniaxial cyclic loading and unloading tests were conducted to measure the elastic strain energy accumulated in sandstone under different stress levels and a relationship between elastic strain energy and stress level was established.The results show that:(1)The peak stress under cyclic loading and unloading conditions is slightly lower than the uniaxial compressive strength.With an increase in the number of cycles,the internal damage of sandstone continues to accumulate,and the mechanical properties such as compressive strength continue to deteriorate;(2)With an increase in stress,the input strain energy,elastic strain energy,and dissipated strain energy also increase;(3)When the stress is low,the increase in elastic strain energy is large and shows a steady growth;with an increase in stress,the increase of elastic strain energy decreases;(4)The square of stress at any time has a good linear relationship with elastic strain energy.According to the relationship obtained from the test,the elastic strain energy at the peak stress time can be obtained;(5)A new criterion for assessing rock burst proneness is proposed:residual energy release rate index W_(T),which characterizes the energy release per unit time when the rock burst occurs.The intervals for evaluating the rock burst proneness of the residual energy release rate index W_(T) are as follows:W_(T)<0.025,indicating no rock burst proneness;0.025≤W_(T)<0.15,indicating weak rock burst proneness;0.15≤W_(T)<2,indicating medium rock burst proneness;W_(T)>2,indicating strong rock burst proneness;and(6)The rationality of the proposed residual energy release rate index W_(T) is verified by the multi-index method and the multi-sample method,and the proposed residual energy release rate index is used to determine the rock burst proneness of 10 kinds of rock samples.The evaluation accuracy is shown to be high,and it can reflect the actual rock burst proneness.
基金Supported by the National Natural Science Foundation of China(52304203,52374180 and 52327804).
文摘In order to study the mechanics,acoustic emission(AE)and electromagnetic emission(EME)response law of bursting liability coal at different loading rates,uniaxial compression tests were carried out on coal mass from Konggu Coal Mine.The corresponding relations among mechanical properties,AE and EME signals in the process of coal failure under loading were analyzed,and the energy evolution law of coal failure with bursting liability under loading rate was discussed.The results show that within a certain range of loading rate,the higher the loading rate,the higher the compressive strength and peak load of bursting liability coal,and the shorter the time for coal to reach the peak load.Under different loading rates,the mechanics,AE and EME signals of coal samples can be well corresponded.When the loading rate is low,the number of blocks destroyed of coal sample is large and the block size is relatively small,and the blocks are mainly scattered around the test platform.When the loading rate is high,the number of damaged blocks is relatively small and the block size is relatively large,and the blocks are far away from the test bench.When loading at a low rate,the internal cracks in coal can be fully developed and connected,and the energy release rate is relatively uniform in the process of loading and failure of coal sample.In the case of high loading rate,the energy release rate of coal sample in the loading process is much smaller than that in the moment of failure.Combining the above test results with the actual situation of the working face,it can be concluded that the total energy stored in the coal of fast mining increases and the threshold of impact decreases compared with that of slow mining.Therefore,under the disturbance of external dynamic load,rapid mining is more likely to induce rock burst.
