Air blasts induced by rock-ice avalanches are common natural phenomena known for their far-field destructive impact.In this study,remote sensing images,eyewitness videos and numerical modelling were comprehensively ap...Air blasts induced by rock-ice avalanches are common natural phenomena known for their far-field destructive impact.In this study,remote sensing images,eyewitness videos and numerical modelling were comprehensively applied to analyze the initiation and propagation of the 2021 Chamoli avalancheinduced air blast.Our findings indicate that air blasts are observed from the avalanche source area to the Rishiganga valley,but nearly disappear in the Dhauliganga valley.The most intense air blast is concentrated on the left side of Ronti Gad valley,with maximum velocity and pressure estimated at over 70 m/s and 20 kPa,respectively.Such high pressure results in widespread tree breakage in the area.Based on the analysis of the Chamoli event,we further discussed the potential contribution of the avalanche flow regime,avalanche dynamics and geomorphology to the destructive potential of air blasts.Rapidly moved sliding mass can impart the air blast a high initial momentum,and this process will be exaggerated when the avalanche impacts valley walls at bends.However,when the rock-ice avalanche transforms into a debris-enriched flash flood,free water within the flowing mass can displace air,inhibiting the generation of air blasts.Our work offers new insights into the generation and propagation of rock-ice avalanche-induced air blasts,underscoring the importance of including this type of hazard during avalanche risk assessment in high-altitude glacial regions.展开更多
To find discriminating features in seismograms for the classification of mine seismic events,signal databases of blasts and microseismic events were established based on manual identification.Criteria including the re...To find discriminating features in seismograms for the classification of mine seismic events,signal databases of blasts and microseismic events were established based on manual identification.Criteria including the repetition of waveforms,tail decreasing,dominant frequency and occurrence time of day were considered in the establishment of the databases.Signals from databases of different types were drawn into a unified coordinate system.It is noticed that the starting-up angles of the two types tend to be concentrated into two different intervals.However,it is difficult to calculate the starting-up angle directly due to the inaccuracy of the P-wave arrival＇s picking.The slope value of the starting-up trend line,which was obtained by linear regression,was proposed to substitute the angle.Two slope values associated with the coordinates of the first peak and the maximum peak were extracted as the characteristic parameters.A statistical model with correct discrimination rate of greater than 97.1% was established by applying the Fisher discriminant analysis.展开更多
Microseismic monitoring system is one of the effective methods for deep mining geo-stress monitoring.The principle of microseismic monitoring system is to analyze the mechanical parameters contained in microseismic ev...Microseismic monitoring system is one of the effective methods for deep mining geo-stress monitoring.The principle of microseismic monitoring system is to analyze the mechanical parameters contained in microseismic events for providing accurate information of rockmass.The accurate identification of microseismic events and blasts determines the timeliness and accuracy of early warning of microseismic monitoring technology.An image identification model based on Convolutional Neural Network(CNN)is established in this paper for the seismic waveforms of microseismic events and blasts.Firstly,the training set,test set,and validation set are collected,which are composed of 5250,1500,and 750 seismic waveforms of microseismic events and blasts,respectively.The classified data sets are preprocessed and input into the constructed CNN in CPU mode for training.Results show that the accuracies of microseismic events and blasts are 99.46%and 99.33%in the test set,respectively.The accuracies of microseismic events and blasts are 100%and 98.13%in the validation set,respectively.The proposed method gives superior performance when compared with existed methods.The accuracies of models using logistic regression and artificial neural network(ANN)based on the same data set are 54.43%and 67.9%in the test set,respectively.Then,the ROC curves of the three models are obtained and compared,which show that the CNN gives an absolute advantage in this classification model when the original seismic waveform are used in training the model.It not only decreases the influence of individual differences in experience,but also removes the errors induced by source and waveform parameters.It is proved that the established discriminant method improves the efficiency and accuracy of microseismic data processing for monitoring rock instability and seismicity.展开更多
Koyna-Warna is a seismically active region, characterized by earthquakes triggered by loading of artificial water reservoirs. In this region quarrying is ongoing and sometimes the quarry blasts are confused with trigg...Koyna-Warna is a seismically active region, characterized by earthquakes triggered by loading of artificial water reservoirs. In this region quarrying is ongoing and sometimes the quarry blasts are confused with triggered seismic events. About 410 events around a known mining area were ob-served during January 2007-October 2013. In general the quarry blasts are carried out mostly during the day time. Based on this fact a well known method of [1] is implemented, which has the capability of detecting the areas of quarry blast activity. Also, discrimination of quarry blasts from earthquakes has been achieved by studying waveforms at key seismic stations located close to the quarrying area. Further, distinction is achieved through spectral analysis in the frequency band of 3 - 15 Hz. Ratio of day-time to night-time events, waveform pattern and spectral analysis approach confirm the presence of quarry blasts aligned south-east of the Warna reservoir.展开更多
This paper presents a time-efficient numerical approach to modelling high explosive(HE)blastwave propagation using Computational Fluid Dynamics(CFD).One of the main issues of using conventional CFD modelling in high e...This paper presents a time-efficient numerical approach to modelling high explosive(HE)blastwave propagation using Computational Fluid Dynamics(CFD).One of the main issues of using conventional CFD modelling in high explosive simulations is the ability to accurately define the initial blastwave properties that arise from the ignition and consequent explosion.Specialised codes often employ Jones-Wilkins-Lee(JWL)or similar equation of state(EOS)to simulate blasts.However,most available CFD codes are limited in terms of EOS modelling.They are restrictive to the Ideal Gas Law(IGL)for compressible flows,which is generally unsuitable for blast simulations.To this end,this paper presents a numerical approach to simulate blastwave propagation for any generic CFD code using the IGL EOS.A new method known as the Input Cavity Method(ICM)is defined where input conditions of the high explosives are given in the form of pressure,velocity and temperature time-history curves.These time history curves are input at a certain distance from the centre of the charge.It is shown that the ICM numerical method can accurately predict over-pressure and impulse time history at measured locations for the incident,reflective and complex multiple reflection scenarios with high numerical accuracy compared to experimental measurements.The ICM is compared to the Pressure Bubble Method(PBM),a common approach to replicating initial conditions for a high explosive in Finite Volume modelling.It is shown that the ICM outperforms the PBM on multiple fronts,such as peak values and overall overpressure curve shape.Finally,the paper also presents the importance of choosing an appropriate solver between the Pressure Based Solver(PBS)and Density-Based Solver(DBS)and provides the advantages and disadvantages of either choice.In general,it is shown that the PBS can resolve and capture the interactions of blastwaves to a higher degree of resolution than the DBS.This is achieved at a much higher computational cost,showing that the DBS is much preferred for quick turnarounds.展开更多
Cup-like nuclear morphological alterations in acute myeloid leukemia(AML)blasts have been widely correlated with Nucleophosmin 1(NPM1)mutations.NPM1-mutated AML has earned recognition as a distinct entity among myeloi...Cup-like nuclear morphological alterations in acute myeloid leukemia(AML)blasts have been widely correlated with Nucleophosmin 1(NPM1)mutations.NPM1-mutated AML has earned recognition as a distinct entity among myeloid tumors,but the absence of a thoroughly established tool for its morphological analysis remains a notable gap.Holographic tomography(HT)can offer a label-free solution for quantitatively assessing the 3D shape of the nucleus based on the volumetric variations of its refractive indices(RIs).However,traditional HT methods analyze adherent cells in a 2D layer,leading to non-isotropic reconstructions due to missing cone artifacts.Here we show for the first time that holo-tomographic flow cytometry(HTFC)achieves quantitative specificity and precise capture of the nucleus volumetric shape in AML cells in suspension.To retrieve nucleus specificity in label-free RI tomograms of flowing AML cells,we conceive and demonstrate in a real-world clinical case a novel strategy for segmenting 3D concave nuclei.This method implies that the correlation between the"phenotype"and"genotype"of nuclei is demonstrated through HTFC by creating a challenging link not yet explored between the aberrant morphological features of AML nuclei and NPM1 mutations.We conduct an ensemble-level statistical characterization of NPM1-wild type and NPM1-mutated blasts to discern their complex morphological and biophysical variances.Our findings suggest that characterizing cup-like nuclei in NPM1-related AML cells by HTFC may enhance the diagnostic approach for these tumors.Furthermore,we integrate virtual reality to provide an immersive fruition of morphological changes in AML cells within a true 3D environment.展开更多
The dynamic response and failure characteristics of tunnels vary significantly under various dynamic disturbances.These characteristics are crucial for assessing structural stability and designing effective support fo...The dynamic response and failure characteristics of tunnels vary significantly under various dynamic disturbances.These characteristics are crucial for assessing structural stability and designing effective support for surrounding rock.In this study,the theoretical solution for the dynamic stress concentration factor(DSCF)of a circular tunnel subjected to cylindrical and plane P-waves was derived using the wave function expansion method.The existing equivalent blast stress wave was optimized and the Ricker wavelet was introduced to represent the seismic stress waves.By combining Fourier transform and Duhamel’s integral,the transient response of the underground tunnel under near-field blasts and far-field earthquakes was determined in both the frequency and time domains.The theoretical results were validated by comparing them with those obtained from numerical simulations using ANSYS LS-DYNA software.Numerical simulations were conducted to further investigate the damage characteristics of the underground tunnel and evaluate the effect of initial stress on structural failure under both types of disturbances.The theoretical and numerical simulation results indicated that the differences in the dynamic response and damage characteristics of the underground tunnel were primarily due to the curvature of the stress waves and transient load waveform.The locations of the maximum DSCF values differed between near-field blasts and far-field earthquakes,whereas the minimum DSCF values occurred at the same positions.Without initial stress,the blast stress waves caused spalling damage to the rock mass on the wave-facing side.Shear failure occurred near the areas with maximum DSCF values,and tensile failure occurred near the areas with minimum DSCF values.In contrast,damage occurred only near the areas with maximum DSCF values under seismic stress waves.Furthermore,the initial stress exacerbated spalling and shear damage while suppressing tensile failure.Hence,the blast stress waves no longer induced tensile failure on the tunnel sidewalls under initial stress.展开更多
The purpose of this research is to demonstrate the use of Adaptive Neuro-Fuzzy Inference System(ANFIS)for discrimination between quarry blasts and microearthquakes in the Tehran region using data from the Broadband Ir...The purpose of this research is to demonstrate the use of Adaptive Neuro-Fuzzy Inference System(ANFIS)for discrimination between quarry blasts and microearthquakes in the Tehran region using data from the Broadband Iranian National Network Center(BIN).In the south and southeast of Tehran,a large number of quarry blasts“contaminate”the earthquake catalog.In order to identify the real seismicity(tectonic earthquakes)in the region,we need to discriminate quarry blasts from natural earthquakes in the catalog.展开更多
Natural and human-made hazards pose significant risks to bridges,disrupting transportation systems and causing severe economic and social impacts.Earthquakes and blasts are particularly critical in evaluating long-ter...Natural and human-made hazards pose significant risks to bridges,disrupting transportation systems and causing severe economic and social impacts.Earthquakes and blasts are particularly critical in evaluating long-term bridge resilience.Current resilience assessment methods,however,focus primarily on single and deterministic hazards,neglecting the uncertainty associated with hazard randomness,hazard interrelationship,structural robustness,and variability in restoration.This can underestimate risks and lead to structural failures,highlighting a critical knowledge gap.This paper proposes a novel approach to assess bridge resilience under multi-hazards,specifically earthquakes and blasts.The approach incorporates underexplored uncertainties,accounts for damage accumulation through state-dependent fragility,and introduces the resilience quantification probabilistically.An illustrative case study demonstrates its application,showing that hazard randomness,particularly the sequence and timing of sequential hazards during restoration,significantly influences bridge resilience.The findings emphasize the importance of detailed and probabilistic consideration of hazard randomness and interrelationship in the multi-hazard context.The proposed approach has the potential for broader application to other hazard types and structural systems,addressing an urgent need for resilience assessment in infrastructure systems subjected to multiple hazards.展开更多
Predicting rock blasting outcomes in mining has been crucial since its inception.Blasting remains the most energy-and cost-efficient method for rock breaking and is often the only practical option.However,the mechanis...Predicting rock blasting outcomes in mining has been crucial since its inception.Blasting remains the most energy-and cost-efficient method for rock breaking and is often the only practical option.However,the mechanism is complex,influenced by various rock properties,explosives,and blast design parameters,making their effects difficult to quantify.Traditional stress-based models struggle with many parameters,such as stress and Poisson's ratio,which are challenging to measure in the field.Empirical models,though simpler,often oversimplify blast conditions.Both types of models are limited to simulating a few blastholes and cannot handle full-scale blasts involving hundreds of blastholes.However,modeling full-scale blasts with all blast design parameters is most required for modern mining applications.This paper presents a novel strain-based modeling approach for blasting and geomechanical applications,utilizing measurable variables such as particle velocity,strain,and displacement.By bypassing complex constitutive relations,strain-based models capture critical blasting trends and simulate full-scale blasts with full-blast design parameters with minimal calibration.The framework encompasses field strain measurements,model construction based on measurable variables,and laboratoryderived strain-failure criteria,each offering potential for future enhancement.Additionally,a standardized field test for site characterization is recommended.The approach is demonstrated through the Multiple Blasthole Fragmentation model,which simulates rock fragmentation and fragment strain during blasting,highlighting the practicality and effectiveness of strain-based modeling for multiple blasthole blasts.Moreover,this approach extends beyond blasting,with potential applications in highwall stability monitoring and other geomechanical applications.Strain-based modeling provides a simplified yet effective solution,avoiding the complexities of rock constitutive relations and field stress measurements while enabling full-blast design simulations for large-scale field blasts.展开更多
Background Rapid clearance of peripheral blood blasts （PBBs） predicts complete remission （CR） and survival in patients with acute myeloid leukemia （AML）.We aimed to explore the correlation between induction ther...Background Rapid clearance of peripheral blood blasts （PBBs） predicts complete remission （CR） and survival in patients with acute myeloid leukemia （AML）.We aimed to explore the correlation between induction therapy response,outcome,and the PBB percentage.Methods Forty-six consecutive patients with de novo AML （excluding acute promyelocytic leukemia） were enrolled in this study.Flow cytometry was performed to identify cells with a leukemia-associated aberrant immunophenotype in the initial bone marrow aspirate and in peripheral blood on day 7 of induction therapy.Results The PBB percentage on day 7 （D7PBBP） was significantly lower in patients who achieved CR （0.03% （0.0%,0.45%）） than in those who did not （10.85% （1.13%,19.38%）; u =-3.92,P 〈0.001）.The CR rate was significantly higher among patients with a D7PBBP of 〈0.945% （84.62%,22/26） than among those with a D7PBBP of 〉0.945% （25.0%,5/20;Х^2 =16.571,P 〈0.001）.D7PBBP was significantly correlated with overall survival （OS; r=-0.437,P=0.003） and relapsefree survival （RFS; r=-0.388,P=0.007）.OS and RFS were significantly higher in patients with a D7PBBP of 〈0.43% than in those with a D7PBBP of 〉0.43% （P 〈0.001 and P=0.039,respectively）.D7PBBP was also found to be an independent prognostic indicator in multivariate analysis for both OS （P=-0.036） and RFS （P=0.035）.Conclusion D7PBBP may be an important risk factor for the achievement of complete remission,for overall survival,and for relapse-free survival.展开更多
Reinforced concrete(RC)beams face potential near-field blast threats as key structural components in building structures.To investigate the failure modes and dynamic responses of RC beams subjected to near-field blast...Reinforced concrete(RC)beams face potential near-field blast threats as key structural components in building structures.To investigate the failure modes and dynamic responses of RC beams subjected to near-field blast loading,this paper presents both blast tests and numerical simulation studies on RC beams.First,near-field blast tests were conducted on five RC beam specimens under strong and weak-axis bending loading.Then,a refined finite element model of RC beams was established to verify the applicability of the adopted finite element analysis method.Finally,based on the calibrated finite element model,the failure mechanisms of RC beams were explored,and the influence of blast incidence angle on the failure modes and dynamic responses of RC beams was investigated.The results indicate:(i)Near-field blast loading demonstrates pronounced non-uniform distribution patterns.Under strong-axis incidence,clearing effects beyond the mid-span region are more significant than weak-axis incidence,leading to accelerated impulse attenuation.(ii)Three consecutive developmental stages primarily control the damage mechanism of RC beams:stress wave-induced local damage,local deformation causing plastic hinge propagation,and free vibration of the beam;(iii)As the scaled distance decreases,the failure mode of RC beams under weak-axis blast loading evolves from flexural failure to local failure.The resistance mechanism of RC beams under weak-axis blast loading is more prone to transition from compressive membrane action to tensile membrane action,reducing their blast resistance capacity;(iv)As the explosion incident angleθincreases from 0°to 90°,the blast wave-structure interaction transitions from regular reflection to Mach reflection and back to normal reflection,causing the dynamic response of RC beams to first decrease then increase,with corner concrete spalling damage being the primary failure mode.展开更多
Deep mining of natural resources,like coal,is increasingly utilizing directional blasting technology with slit charge for rock blasting at greater depths.This study,based on numerical simulation methods,analyzes the d...Deep mining of natural resources,like coal,is increasingly utilizing directional blasting technology with slit charge for rock blasting at greater depths.This study,based on numerical simulation methods,analyzes the dynamic behavior of slit charge blasting in three aspects:slit tube dynamic response,hoop stress evolution,and crack propagation.According to research findings,the failure mode of the slit tube mainly manifests as a tensile fracture of the inner wall and a shear fracture at the end connection,where the end connection of the slit tube is the weak point of the overall structure.The dynamic response of the slit tube mainly exhibits radial response in the vertical direction of the slit and hoop response in the slit direction.The hoop tensile stress plays a crucial role in determining the spread of cracks caused by explosions.As the in situ stress increases,the peak hoop tensile stress reduces,and the peak hoop compressive stress increases.This hinders the propagation of cracks.In addition,the directional impact is most pronounced in the middle of the borehole,with the longest primary directional crack observed.Conversely,the directional impact is least favorable near the bottom of the borehole.When the in situ stress reaches 60MPa,the purpose of directional fracture has not been achieved,suggesting combining presplit blasting for in situ stress relief to improve rock breaking efficiency.展开更多
This research is focused on the calculation of a reasonable detonator delay time for realizing cut blast vibration control.First,the viscoelastic rock mass parameters corresponding to the engineering rock mass quality...This research is focused on the calculation of a reasonable detonator delay time for realizing cut blast vibration control.First,the viscoelastic rock mass parameters corresponding to the engineering rock mass quality classification were determined based on wave theory of Kelvin medium.Then,a calculation model was obtained for the millisecond-delay cut blast vibration in Kelvin media using the Starfield charge superposition principle.Further,the influence of the delay time on the cut blast vibration was quantitatively analyzed and a method for calculating the reasonable cut blasting millisecond delay time is proposed according to the principle of dimensional analysis.Finally,field tests were used to verify the applicability of the method.The results show that 5 ms to 20 ms is a better detonator delay time range and cut blasting vibration can be effectively controlled using the delay time calculated by the calculation model described in this paper.展开更多
Burden is one of the main parameters in blast design.However,field tests,either single-or multi-hole blasts,used to determine an appropriate burden,are difficult to capture crack propagation,evolution of breakage angl...Burden is one of the main parameters in blast design.However,field tests,either single-or multi-hole blasts,used to determine an appropriate burden,are difficult to capture crack propagation,evolution of breakage angle,and the mechanism governing these processes in the rock.In this study,a single-hole bench blasting model is developed using LS-DYNA software to comprehensively investigate the relationship between burden and rock breakage.The simulation results show that the breakage angle decreases with the increase in burden,and the blasted volume reaches a peak value with a burden of 4 m.Meanwhile,backbreak distance increases with increasing burden.The optimum burden in this simulation is found to be 4.0 m,as the ratio of burden to blasthole diameter is equal to 20.62 and the ratio of burden to bench height is 0.44,based on a comprehensive analysis of the blasted volume,average damage,and total damage.Under the optimum burden condition,tensile stress wave regions are simultaneously generated at the free surfaces of both the bench top and bench slope,allowing more effective utilization of the two free surfaces and resulting in a more uniform damage distribution within the burden region.展开更多
To address the kinetic constraints inherent in the catalytic combustion of pulverized coal injection under low heating-rate conditions within conventional air atmospheres,a drop tube furnace was utilized to simulate t...To address the kinetic constraints inherent in the catalytic combustion of pulverized coal injection under low heating-rate conditions within conventional air atmospheres,a drop tube furnace was utilized to simulate the catalytic combustion of pulverized coal(PC).The effects of gas composition,oxygen concentration,the type,and the content of catalysts on the combustion reactivity were systematically analyzed.Furthermore,the structural changes of unburned pulverized coal were also examined.Experimental results indicate that as the oxygen concentration increased from 21%to 79%,compared with the O_(2)/N_(2)condition,the increment in the burnout rate of PC under the O_(2)/CO_(2)condition increased from 3%to 23%.After the addition of catalysts,including hematite,metallurgical oil sludge,and light-burnt dolomite(LBD),under the condition of 21%oxygen concentration,the effects of the three catalysts under the O_(2)/CO_(2)condition were superior to those under the O_(2)/N_(2)condition.This trend was reversed under the conditions of 38%and 79%oxygen concentrations.In all atmospheres,the three catalysts can enhance the burnout rate of PC.Among them,LBD exhibits the most favorable effect,and there exists an optimal dosage.Mechanistic analysis through scanning electron microscopy,X-ray diffraction,and N_(2)adsorption-desorption reveals that under 21%O_(2)/79%CO_(2)conditions,high-concentration CO_(2)leads to the formation of pores,and additives accelerate the oxidation of C and the gasification of CO_(2)through oxygen transfer,thereby enhancing the burnout rate of PC.展开更多
Gravity-caisson wharves have been widely constructed in coastal and island regions, which are threaten by potential underwater explosions. This work aims to study the dynamic behaviors and propose a damage evaluation ...Gravity-caisson wharves have been widely constructed in coastal and island regions, which are threaten by potential underwater explosions. This work aims to study the dynamic behaviors and propose a damage evaluation approach of caisson wharf against underwater explosion. Firstly, based on both the underwater explosion loading test and underwater explosion test on the reduced-scale caisson specimen, a high-fidelity finite element analysis approach for numerically reproduce the dynamic behaviors of prototype caisson wharves against underwater explosions was proposed and verified. Secondly, the underwater explosion loadings and dynamic behaviors of prototype caisson wharf (14.9 m×8.1 m×10.95 m) against sequential blast wave and bubble pulsation of typical torpedo with a charge weight of 200 kg were studied. The influences of the seabed and cabin infill materials, as well as the explosion standoff distances of 3.4–10.2 m and depths of burst between 1/4 and 3/4 of water depth, on the blast resistance of caisson wharf were further examined through deflection distributions of exterior wall, damage evolution, and overall displacement of caisson wharf. Finally, a performance evaluation approach for prototype caisson wharves against underwater explosions was proposed by comprehensively considering the bearing, storage, and berthing capabilities. The corresponding protective measures and design recommendations were further provided. It indicates that: (i) under the explosion of a typical torpedo, the damage modes of prototype caisson wharf mainly involve the overall vibration, spalling and cracking of the exterior wall, collapse of the upper operating platform and cracking of the top plate;(ii) the blast wave and cavitation zone generated between the bubble and the exterior wall are the two primary causes of damage to caisson wharf;(iii) compared to the saturated calcareous sand seabed, the assumption of rigid seabed underestimates the spalling on the exterior wall, which is not recommended for scenarios where cavitation zones may generate;(iv) rock rubble is the most effective infill material in improving the blast resistance of caisson wharf among four types of infill configurations, i.e., fully filled and half-filled saturated calcareous sand, rock rubble and pure water;(v) the standoff distance of 10.2 m is regarded as a secure protective range in the scenarios discussed currently. As the standoff distance decreases and the depth of burst increases, the spalling of the exterior wall induced by the cavitation intensifies, posing a great threat to the functionality of caisson wharf.展开更多
Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at ...Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.展开更多
Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate ...Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate this challenge,we present an enhanced semi-supervised learning approach based on the Mean Teacher framework,incorporating a novel feature loss module to maximize classification performance with limited labeled samples.The model studies show that the proposed model surpasses both the baseline Mean Teacher model and fully supervised method in accuracy.Specifically,for datasets with 20%,30%,and 40%label ratios,using a single training iteration,the model yields accuracies of 78.61%,82.21%,and 85.2%,respectively,while multiple-cycle training iterations achieves 82.09%,81.97%,and 81.59%,respectively.Furthermore,scenario-specific training schemes are introduced to support diverse deployment need.These findings highlight the potential of the proposed technique in minimizing labeling requirements and advancing intelligent blast furnace diagnostics.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.U2244227,42277126 and 41977215).
文摘Air blasts induced by rock-ice avalanches are common natural phenomena known for their far-field destructive impact.In this study,remote sensing images,eyewitness videos and numerical modelling were comprehensively applied to analyze the initiation and propagation of the 2021 Chamoli avalancheinduced air blast.Our findings indicate that air blasts are observed from the avalanche source area to the Rishiganga valley,but nearly disappear in the Dhauliganga valley.The most intense air blast is concentrated on the left side of Ronti Gad valley,with maximum velocity and pressure estimated at over 70 m/s and 20 kPa,respectively.Such high pressure results in widespread tree breakage in the area.Based on the analysis of the Chamoli event,we further discussed the potential contribution of the avalanche flow regime,avalanche dynamics and geomorphology to the destructive potential of air blasts.Rapidly moved sliding mass can impart the air blast a high initial momentum,and this process will be exaggerated when the avalanche impacts valley walls at bends.However,when the rock-ice avalanche transforms into a debris-enriched flash flood,free water within the flowing mass can displace air,inhibiting the generation of air blasts.Our work offers new insights into the generation and propagation of rock-ice avalanche-induced air blasts,underscoring the importance of including this type of hazard during avalanche risk assessment in high-altitude glacial regions.
基金Projects(51374244,11447241)supported by the National Natural Science Foundation of China
文摘To find discriminating features in seismograms for the classification of mine seismic events,signal databases of blasts and microseismic events were established based on manual identification.Criteria including the repetition of waveforms,tail decreasing,dominant frequency and occurrence time of day were considered in the establishment of the databases.Signals from databases of different types were drawn into a unified coordinate system.It is noticed that the starting-up angles of the two types tend to be concentrated into two different intervals.However,it is difficult to calculate the starting-up angle directly due to the inaccuracy of the P-wave arrival＇s picking.The slope value of the starting-up trend line,which was obtained by linear regression,was proposed to substitute the angle.Two slope values associated with the coordinates of the first peak and the maximum peak were extracted as the characteristic parameters.A statistical model with correct discrimination rate of greater than 97.1% was established by applying the Fisher discriminant analysis.
基金Projects(51822407,51774327,51664016)supported by the National Natural Science Foundation of China。
文摘Microseismic monitoring system is one of the effective methods for deep mining geo-stress monitoring.The principle of microseismic monitoring system is to analyze the mechanical parameters contained in microseismic events for providing accurate information of rockmass.The accurate identification of microseismic events and blasts determines the timeliness and accuracy of early warning of microseismic monitoring technology.An image identification model based on Convolutional Neural Network(CNN)is established in this paper for the seismic waveforms of microseismic events and blasts.Firstly,the training set,test set,and validation set are collected,which are composed of 5250,1500,and 750 seismic waveforms of microseismic events and blasts,respectively.The classified data sets are preprocessed and input into the constructed CNN in CPU mode for training.Results show that the accuracies of microseismic events and blasts are 99.46%and 99.33%in the test set,respectively.The accuracies of microseismic events and blasts are 100%and 98.13%in the validation set,respectively.The proposed method gives superior performance when compared with existed methods.The accuracies of models using logistic regression and artificial neural network(ANN)based on the same data set are 54.43%and 67.9%in the test set,respectively.Then,the ROC curves of the three models are obtained and compared,which show that the CNN gives an absolute advantage in this classification model when the original seismic waveform are used in training the model.It not only decreases the influence of individual differences in experience,but also removes the errors induced by source and waveform parameters.It is proved that the established discriminant method improves the efficiency and accuracy of microseismic data processing for monitoring rock instability and seismicity.
文摘Koyna-Warna is a seismically active region, characterized by earthquakes triggered by loading of artificial water reservoirs. In this region quarrying is ongoing and sometimes the quarry blasts are confused with triggered seismic events. About 410 events around a known mining area were ob-served during January 2007-October 2013. In general the quarry blasts are carried out mostly during the day time. Based on this fact a well known method of [1] is implemented, which has the capability of detecting the areas of quarry blast activity. Also, discrimination of quarry blasts from earthquakes has been achieved by studying waveforms at key seismic stations located close to the quarrying area. Further, distinction is achieved through spectral analysis in the frequency band of 3 - 15 Hz. Ratio of day-time to night-time events, waveform pattern and spectral analysis approach confirm the presence of quarry blasts aligned south-east of the Warna reservoir.
文摘This paper presents a time-efficient numerical approach to modelling high explosive(HE)blastwave propagation using Computational Fluid Dynamics(CFD).One of the main issues of using conventional CFD modelling in high explosive simulations is the ability to accurately define the initial blastwave properties that arise from the ignition and consequent explosion.Specialised codes often employ Jones-Wilkins-Lee(JWL)or similar equation of state(EOS)to simulate blasts.However,most available CFD codes are limited in terms of EOS modelling.They are restrictive to the Ideal Gas Law(IGL)for compressible flows,which is generally unsuitable for blast simulations.To this end,this paper presents a numerical approach to simulate blastwave propagation for any generic CFD code using the IGL EOS.A new method known as the Input Cavity Method(ICM)is defined where input conditions of the high explosives are given in the form of pressure,velocity and temperature time-history curves.These time history curves are input at a certain distance from the centre of the charge.It is shown that the ICM numerical method can accurately predict over-pressure and impulse time history at measured locations for the incident,reflective and complex multiple reflection scenarios with high numerical accuracy compared to experimental measurements.The ICM is compared to the Pressure Bubble Method(PBM),a common approach to replicating initial conditions for a high explosive in Finite Volume modelling.It is shown that the ICM outperforms the PBM on multiple fronts,such as peak values and overall overpressure curve shape.Finally,the paper also presents the importance of choosing an appropriate solver between the Pressure Based Solver(PBS)and Density-Based Solver(DBS)and provides the advantages and disadvantages of either choice.In general,it is shown that the PBS can resolve and capture the interactions of blastwaves to a higher degree of resolution than the DBS.This is achieved at a much higher computational cost,showing that the DBS is much preferred for quick turnarounds.
基金supported by the project PRIN 2022 PNRR—flow-cytometry ImaGing by Holographic tomography for predicting TUMor control in Oncology patients treated with Radiotherapy(FIGHT-TUMOR),Prot.P2022ATE2J—funded by the Italian Ministry of University&Research in the framework of Next Generation EUby project“CITOM”—Programma AMICO 2,CNR—UVR—within the PoC 2022—PNRR funded by the Italian Ministry of Business and Made in Italy—UIBM in the framework of Next Generation EUby#NEXTGENERATIONEU(NGEU),Ministry of University and Research(MUR),National Recovery and Resilience Plan(NRRP),project MNESYS(PE0000006)—a multiscale integrated approach to the study of the nervous system in health and disease(DN.155311.10.2022)。
文摘Cup-like nuclear morphological alterations in acute myeloid leukemia(AML)blasts have been widely correlated with Nucleophosmin 1(NPM1)mutations.NPM1-mutated AML has earned recognition as a distinct entity among myeloid tumors,but the absence of a thoroughly established tool for its morphological analysis remains a notable gap.Holographic tomography(HT)can offer a label-free solution for quantitatively assessing the 3D shape of the nucleus based on the volumetric variations of its refractive indices(RIs).However,traditional HT methods analyze adherent cells in a 2D layer,leading to non-isotropic reconstructions due to missing cone artifacts.Here we show for the first time that holo-tomographic flow cytometry(HTFC)achieves quantitative specificity and precise capture of the nucleus volumetric shape in AML cells in suspension.To retrieve nucleus specificity in label-free RI tomograms of flowing AML cells,we conceive and demonstrate in a real-world clinical case a novel strategy for segmenting 3D concave nuclei.This method implies that the correlation between the"phenotype"and"genotype"of nuclei is demonstrated through HTFC by creating a challenging link not yet explored between the aberrant morphological features of AML nuclei and NPM1 mutations.We conduct an ensemble-level statistical characterization of NPM1-wild type and NPM1-mutated blasts to discern their complex morphological and biophysical variances.Our findings suggest that characterizing cup-like nuclei in NPM1-related AML cells by HTFC may enhance the diagnostic approach for these tumors.Furthermore,we integrate virtual reality to provide an immersive fruition of morphological changes in AML cells within a true 3D environment.
基金supported by the National Natural Science Foundation of China(Grant Nos.52334003 and 52274105)the Fundamental Research Funds for the Central Universities of Central South University(Grant No.CX20240263).
文摘The dynamic response and failure characteristics of tunnels vary significantly under various dynamic disturbances.These characteristics are crucial for assessing structural stability and designing effective support for surrounding rock.In this study,the theoretical solution for the dynamic stress concentration factor(DSCF)of a circular tunnel subjected to cylindrical and plane P-waves was derived using the wave function expansion method.The existing equivalent blast stress wave was optimized and the Ricker wavelet was introduced to represent the seismic stress waves.By combining Fourier transform and Duhamel’s integral,the transient response of the underground tunnel under near-field blasts and far-field earthquakes was determined in both the frequency and time domains.The theoretical results were validated by comparing them with those obtained from numerical simulations using ANSYS LS-DYNA software.Numerical simulations were conducted to further investigate the damage characteristics of the underground tunnel and evaluate the effect of initial stress on structural failure under both types of disturbances.The theoretical and numerical simulation results indicated that the differences in the dynamic response and damage characteristics of the underground tunnel were primarily due to the curvature of the stress waves and transient load waveform.The locations of the maximum DSCF values differed between near-field blasts and far-field earthquakes,whereas the minimum DSCF values occurred at the same positions.Without initial stress,the blast stress waves caused spalling damage to the rock mass on the wave-facing side.Shear failure occurred near the areas with maximum DSCF values,and tensile failure occurred near the areas with minimum DSCF values.In contrast,damage occurred only near the areas with maximum DSCF values under seismic stress waves.Furthermore,the initial stress exacerbated spalling and shear damage while suppressing tensile failure.Hence,the blast stress waves no longer induced tensile failure on the tunnel sidewalls under initial stress.
文摘The purpose of this research is to demonstrate the use of Adaptive Neuro-Fuzzy Inference System(ANFIS)for discrimination between quarry blasts and microearthquakes in the Tehran region using data from the Broadband Iranian National Network Center(BIN).In the south and southeast of Tehran,a large number of quarry blasts“contaminate”the earthquake catalog.In order to identify the real seismicity(tectonic earthquakes)in the region,we need to discriminate quarry blasts from natural earthquakes in the catalog.
基金funded by the National Key Research and Development Program of China(Grant No.2019YFE0112300).
文摘Natural and human-made hazards pose significant risks to bridges,disrupting transportation systems and causing severe economic and social impacts.Earthquakes and blasts are particularly critical in evaluating long-term bridge resilience.Current resilience assessment methods,however,focus primarily on single and deterministic hazards,neglecting the uncertainty associated with hazard randomness,hazard interrelationship,structural robustness,and variability in restoration.This can underestimate risks and lead to structural failures,highlighting a critical knowledge gap.This paper proposes a novel approach to assess bridge resilience under multi-hazards,specifically earthquakes and blasts.The approach incorporates underexplored uncertainties,accounts for damage accumulation through state-dependent fragility,and introduces the resilience quantification probabilistically.An illustrative case study demonstrates its application,showing that hazard randomness,particularly the sequence and timing of sequential hazards during restoration,significantly influences bridge resilience.The findings emphasize the importance of detailed and probabilistic consideration of hazard randomness and interrelationship in the multi-hazard context.The proposed approach has the potential for broader application to other hazard types and structural systems,addressing an urgent need for resilience assessment in infrastructure systems subjected to multiple hazards.
文摘Predicting rock blasting outcomes in mining has been crucial since its inception.Blasting remains the most energy-and cost-efficient method for rock breaking and is often the only practical option.However,the mechanism is complex,influenced by various rock properties,explosives,and blast design parameters,making their effects difficult to quantify.Traditional stress-based models struggle with many parameters,such as stress and Poisson's ratio,which are challenging to measure in the field.Empirical models,though simpler,often oversimplify blast conditions.Both types of models are limited to simulating a few blastholes and cannot handle full-scale blasts involving hundreds of blastholes.However,modeling full-scale blasts with all blast design parameters is most required for modern mining applications.This paper presents a novel strain-based modeling approach for blasting and geomechanical applications,utilizing measurable variables such as particle velocity,strain,and displacement.By bypassing complex constitutive relations,strain-based models capture critical blasting trends and simulate full-scale blasts with full-blast design parameters with minimal calibration.The framework encompasses field strain measurements,model construction based on measurable variables,and laboratoryderived strain-failure criteria,each offering potential for future enhancement.Additionally,a standardized field test for site characterization is recommended.The approach is demonstrated through the Multiple Blasthole Fragmentation model,which simulates rock fragmentation and fragment strain during blasting,highlighting the practicality and effectiveness of strain-based modeling for multiple blasthole blasts.Moreover,this approach extends beyond blasting,with potential applications in highwall stability monitoring and other geomechanical applications.Strain-based modeling provides a simplified yet effective solution,avoiding the complexities of rock constitutive relations and field stress measurements while enabling full-blast design simulations for large-scale field blasts.
基金This work was supported by the Science Foundation of Jilin Province （No. 201115049）.Acknowledgements： We thank Cancer Center of the First Hospital, Bethune Medical College of Jilin University, for their assistance in this work.
文摘Background Rapid clearance of peripheral blood blasts （PBBs） predicts complete remission （CR） and survival in patients with acute myeloid leukemia （AML）.We aimed to explore the correlation between induction therapy response,outcome,and the PBB percentage.Methods Forty-six consecutive patients with de novo AML （excluding acute promyelocytic leukemia） were enrolled in this study.Flow cytometry was performed to identify cells with a leukemia-associated aberrant immunophenotype in the initial bone marrow aspirate and in peripheral blood on day 7 of induction therapy.Results The PBB percentage on day 7 （D7PBBP） was significantly lower in patients who achieved CR （0.03% （0.0%,0.45%）） than in those who did not （10.85% （1.13%,19.38%）; u =-3.92,P 〈0.001）.The CR rate was significantly higher among patients with a D7PBBP of 〈0.945% （84.62%,22/26） than among those with a D7PBBP of 〉0.945% （25.0%,5/20;Х^2 =16.571,P 〈0.001）.D7PBBP was significantly correlated with overall survival （OS; r=-0.437,P=0.003） and relapsefree survival （RFS; r=-0.388,P=0.007）.OS and RFS were significantly higher in patients with a D7PBBP of 〈0.43% than in those with a D7PBBP of 〉0.43% （P 〈0.001 and P=0.039,respectively）.D7PBBP was also found to be an independent prognostic indicator in multivariate analysis for both OS （P=-0.036） and RFS （P=0.035）.Conclusion D7PBBP may be an important risk factor for the achievement of complete remission,for overall survival,and for relapse-free survival.
基金supported by the National Natural Science Foundation of China(Grant Nos.52178445,52578544)Open Research Fund of State Key Laboratory of Target Vulnerability Assessment,Defense Engineering Institute,AMS(Grant No.YSX2024KFYS002).
文摘Reinforced concrete(RC)beams face potential near-field blast threats as key structural components in building structures.To investigate the failure modes and dynamic responses of RC beams subjected to near-field blast loading,this paper presents both blast tests and numerical simulation studies on RC beams.First,near-field blast tests were conducted on five RC beam specimens under strong and weak-axis bending loading.Then,a refined finite element model of RC beams was established to verify the applicability of the adopted finite element analysis method.Finally,based on the calibrated finite element model,the failure mechanisms of RC beams were explored,and the influence of blast incidence angle on the failure modes and dynamic responses of RC beams was investigated.The results indicate:(i)Near-field blast loading demonstrates pronounced non-uniform distribution patterns.Under strong-axis incidence,clearing effects beyond the mid-span region are more significant than weak-axis incidence,leading to accelerated impulse attenuation.(ii)Three consecutive developmental stages primarily control the damage mechanism of RC beams:stress wave-induced local damage,local deformation causing plastic hinge propagation,and free vibration of the beam;(iii)As the scaled distance decreases,the failure mode of RC beams under weak-axis blast loading evolves from flexural failure to local failure.The resistance mechanism of RC beams under weak-axis blast loading is more prone to transition from compressive membrane action to tensile membrane action,reducing their blast resistance capacity;(iv)As the explosion incident angleθincreases from 0°to 90°,the blast wave-structure interaction transitions from regular reflection to Mach reflection and back to normal reflection,causing the dynamic response of RC beams to first decrease then increase,with corner concrete spalling damage being the primary failure mode.
基金National Natural Science Foundation of China,Grant/Award Numbers:52204085,52227805。
文摘Deep mining of natural resources,like coal,is increasingly utilizing directional blasting technology with slit charge for rock blasting at greater depths.This study,based on numerical simulation methods,analyzes the dynamic behavior of slit charge blasting in three aspects:slit tube dynamic response,hoop stress evolution,and crack propagation.According to research findings,the failure mode of the slit tube mainly manifests as a tensile fracture of the inner wall and a shear fracture at the end connection,where the end connection of the slit tube is the weak point of the overall structure.The dynamic response of the slit tube mainly exhibits radial response in the vertical direction of the slit and hoop response in the slit direction.The hoop tensile stress plays a crucial role in determining the spread of cracks caused by explosions.As the in situ stress increases,the peak hoop tensile stress reduces,and the peak hoop compressive stress increases.This hinders the propagation of cracks.In addition,the directional impact is most pronounced in the middle of the borehole,with the longest primary directional crack observed.Conversely,the directional impact is least favorable near the bottom of the borehole.When the in situ stress reaches 60MPa,the purpose of directional fracture has not been achieved,suggesting combining presplit blasting for in situ stress relief to improve rock breaking efficiency.
基金National Natural Science Foundation of China under Grant Nos.51979205 and 51939008。
文摘This research is focused on the calculation of a reasonable detonator delay time for realizing cut blast vibration control.First,the viscoelastic rock mass parameters corresponding to the engineering rock mass quality classification were determined based on wave theory of Kelvin medium.Then,a calculation model was obtained for the millisecond-delay cut blast vibration in Kelvin media using the Starfield charge superposition principle.Further,the influence of the delay time on the cut blast vibration was quantitatively analyzed and a method for calculating the reasonable cut blasting millisecond delay time is proposed according to the principle of dimensional analysis.Finally,field tests were used to verify the applicability of the method.The results show that 5 ms to 20 ms is a better detonator delay time range and cut blasting vibration can be effectively controlled using the delay time calculated by the calculation model described in this paper.
基金supported by the European Union in the frame of Horizon Europe AVANTIS project,Grant Agreement No.101137552.
文摘Burden is one of the main parameters in blast design.However,field tests,either single-or multi-hole blasts,used to determine an appropriate burden,are difficult to capture crack propagation,evolution of breakage angle,and the mechanism governing these processes in the rock.In this study,a single-hole bench blasting model is developed using LS-DYNA software to comprehensively investigate the relationship between burden and rock breakage.The simulation results show that the breakage angle decreases with the increase in burden,and the blasted volume reaches a peak value with a burden of 4 m.Meanwhile,backbreak distance increases with increasing burden.The optimum burden in this simulation is found to be 4.0 m,as the ratio of burden to blasthole diameter is equal to 20.62 and the ratio of burden to bench height is 0.44,based on a comprehensive analysis of the blasted volume,average damage,and total damage.Under the optimum burden condition,tensile stress wave regions are simultaneously generated at the free surfaces of both the bench top and bench slope,allowing more effective utilization of the two free surfaces and resulting in a more uniform damage distribution within the burden region.
基金the National Natural Science Foundation of China(No.52374347)Yulin Science and Technology Program Project(No.2024-SF-227)Key Research and Development Program of Shaanxi(No.2021GY-128).
文摘To address the kinetic constraints inherent in the catalytic combustion of pulverized coal injection under low heating-rate conditions within conventional air atmospheres,a drop tube furnace was utilized to simulate the catalytic combustion of pulverized coal(PC).The effects of gas composition,oxygen concentration,the type,and the content of catalysts on the combustion reactivity were systematically analyzed.Furthermore,the structural changes of unburned pulverized coal were also examined.Experimental results indicate that as the oxygen concentration increased from 21%to 79%,compared with the O_(2)/N_(2)condition,the increment in the burnout rate of PC under the O_(2)/CO_(2)condition increased from 3%to 23%.After the addition of catalysts,including hematite,metallurgical oil sludge,and light-burnt dolomite(LBD),under the condition of 21%oxygen concentration,the effects of the three catalysts under the O_(2)/CO_(2)condition were superior to those under the O_(2)/N_(2)condition.This trend was reversed under the conditions of 38%and 79%oxygen concentrations.In all atmospheres,the three catalysts can enhance the burnout rate of PC.Among them,LBD exhibits the most favorable effect,and there exists an optimal dosage.Mechanistic analysis through scanning electron microscopy,X-ray diffraction,and N_(2)adsorption-desorption reveals that under 21%O_(2)/79%CO_(2)conditions,high-concentration CO_(2)leads to the formation of pores,and additives accelerate the oxidation of C and the gasification of CO_(2)through oxygen transfer,thereby enhancing the burnout rate of PC.
基金supported by National Natural Science Foundations of China(Grant No.52308522).
文摘Gravity-caisson wharves have been widely constructed in coastal and island regions, which are threaten by potential underwater explosions. This work aims to study the dynamic behaviors and propose a damage evaluation approach of caisson wharf against underwater explosion. Firstly, based on both the underwater explosion loading test and underwater explosion test on the reduced-scale caisson specimen, a high-fidelity finite element analysis approach for numerically reproduce the dynamic behaviors of prototype caisson wharves against underwater explosions was proposed and verified. Secondly, the underwater explosion loadings and dynamic behaviors of prototype caisson wharf (14.9 m×8.1 m×10.95 m) against sequential blast wave and bubble pulsation of typical torpedo with a charge weight of 200 kg were studied. The influences of the seabed and cabin infill materials, as well as the explosion standoff distances of 3.4–10.2 m and depths of burst between 1/4 and 3/4 of water depth, on the blast resistance of caisson wharf were further examined through deflection distributions of exterior wall, damage evolution, and overall displacement of caisson wharf. Finally, a performance evaluation approach for prototype caisson wharves against underwater explosions was proposed by comprehensively considering the bearing, storage, and berthing capabilities. The corresponding protective measures and design recommendations were further provided. It indicates that: (i) under the explosion of a typical torpedo, the damage modes of prototype caisson wharf mainly involve the overall vibration, spalling and cracking of the exterior wall, collapse of the upper operating platform and cracking of the top plate;(ii) the blast wave and cavitation zone generated between the bubble and the exterior wall are the two primary causes of damage to caisson wharf;(iii) compared to the saturated calcareous sand seabed, the assumption of rigid seabed underestimates the spalling on the exterior wall, which is not recommended for scenarios where cavitation zones may generate;(iv) rock rubble is the most effective infill material in improving the blast resistance of caisson wharf among four types of infill configurations, i.e., fully filled and half-filled saturated calcareous sand, rock rubble and pure water;(v) the standoff distance of 10.2 m is regarded as a secure protective range in the scenarios discussed currently. As the standoff distance decreases and the depth of burst increases, the spalling of the exterior wall induced by the cavitation intensifies, posing a great threat to the functionality of caisson wharf.
基金supported by the Shenzhen Stability Support Plan(Grant No.20231122095154003)National Natural Science Foundation of China(Grant Nos.51978671 and 52422807).
文摘Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.
基金financial support provided by the Natural Science Foundation of Hebei Province,China(No.E2024105036)the Tangshan Talent Funding Project,China(Nos.B202302007 and A2021110015)+1 种基金the National Natural Science Foundation of China(No.52264042)the Australian Research Council(No.IH230100010)。
文摘Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate this challenge,we present an enhanced semi-supervised learning approach based on the Mean Teacher framework,incorporating a novel feature loss module to maximize classification performance with limited labeled samples.The model studies show that the proposed model surpasses both the baseline Mean Teacher model and fully supervised method in accuracy.Specifically,for datasets with 20%,30%,and 40%label ratios,using a single training iteration,the model yields accuracies of 78.61%,82.21%,and 85.2%,respectively,while multiple-cycle training iterations achieves 82.09%,81.97%,and 81.59%,respectively.Furthermore,scenario-specific training schemes are introduced to support diverse deployment need.These findings highlight the potential of the proposed technique in minimizing labeling requirements and advancing intelligent blast furnace diagnostics.
