Understanding how thermal damage accumulates in granites under cyclic thermal loading is crucial for geoengineering design and stability assessment.Two types of granite with different grain sizes were subjected to mul...Understanding how thermal damage accumulates in granites under cyclic thermal loading is crucial for geoengineering design and stability assessment.Two types of granite with different grain sizes were subjected to multiple heating and cooling cycles at identical or increasing target temperatures using a new apparatus.Acoustic emission(AE)and thermal deformation were monitored simultaneously.Ultrasonic velocity,porosity,and permeability measurements,compression tests,and thin-section petrography were conducted to assess the thermal damage and physical and mechanical properties of the treated specimens.The results indicate that the thermal damage progression exhibits cycle-dependent decay at 300℃,and the thermal deformation tends to be elastic.However,the uniaxial compressive strength(UCS)increases after thermal treatment,though the increment decreases with progressive cycles(from 21%to 4%for coarse-grained granite).Progressive temperature cycling induces cumulative damage amplification,manifested by tremendous thermal cracking(the total number of AE hits reaches-170 and 180 times that of the first cycle)and crack density escalation(the crack density reaches-1.6 and 2 times that of the first cycle).AE results reveal that there is a temperature-memory effect in both rock types,and show that thermal stresses are insufficient to generate new thermal damage until the prior exposed temperature is exceeded.Additionally,thermal damage is related to the microstructure of rock:coarse-grained granite with more pre-existing cracks exhibits heating-dominated damage(e.g.94%of the AE energy was generated during heating at 300℃),while fine-grained granite with less inherent damage is more sensitive to cooling(e.g.71%of the AE energy was generated during cooling).Quantitative relationship among P-wave velocity,Young's modulus,and linear crack density provide a good estimation of thermal damage,and can guide assessments of the durability of underground engineering.展开更多
The uniaxial compression tests for mudstone specimens are carried out with four different loading rates from room temperature to 400℃ by using the Rock Mechanics Servo-controlled Testing System MTS810 and high temper...The uniaxial compression tests for mudstone specimens are carried out with four different loading rates from room temperature to 400℃ by using the Rock Mechanics Servo-controlled Testing System MTS810 and high temperature furnace MTS652.02.The mechanical properties of mudstone with various loading rates are studied under different temperature conditions.The results show that when temperature increases from room temperature to 400℃ and loading rate is less than 0.03 mm/s,the peak strength of mudstone specimen decreases as loading rate increases,while the various peak strengths show significant differences when loading rate exceeds 0.03 mm/s.At room temperature,the elastic modulus decreases at the first time and then increases with loading rate rising.When the temperature is between200 and 400℃,the elastic modulus presents a decreasing trend with increasing loading rate.With increasing the loading rate,the number of fragments in mudstone becomes larger and even the powder is observed in mudstone with higher loading rate.Under high loading rate,the failure mode of mudstone specimens under different temperatures is mainly conical damage.展开更多
Skin thermal damage or skin burns are the most commonly encountered type of trauma in civilian and military communities. Besides, advances in laser, microwave and similar technologies have led to recent developments o...Skin thermal damage or skin burns are the most commonly encountered type of trauma in civilian and military communities. Besides, advances in laser, microwave and similar technologies have led to recent developments of thermal treatments for disease and damage involving skin tissue, where the objective is to induce thermal damage precisely within targeted tissue structures but without affecting the surrounding, healthy tissue. Further, extended pain sensation induced by thermal damage has also brought great problem for burn patients. Thus, it is of great importance to quantify the thermal damage in skin tissue. In this paper, the available models and experimental methods for quantification of thermal damage in skin tissue are discussed.展开更多
Magnetic particle imaging(MPI)technology can generate a real-time magnetic nanoparticle(MNP)distribution image for biological tissues,and its use can overcome the limitations imposed in magnetic hyperthermia treatment...Magnetic particle imaging(MPI)technology can generate a real-time magnetic nanoparticle(MNP)distribution image for biological tissues,and its use can overcome the limitations imposed in magnetic hyperthermia treatments by the unpredictable MNP distribution after the intratumoral injection of nanofluid.However,the MNP concentration distribution is generally difficult to be extracted from MPI images.This study proposes an approach to extract the corresponding concentration value of each pixel from an MPI image by a least squares method(LSM),which is then translated as MNP concentration distribution by an interpolation function.The resulting MPI-based concentration distribution is used to evaluate the treatment effect and the results are compared with the ones of two baseline cases under the same dose:uniform distribution and MPI-based distribution considering diffusion.Additionally,the treatment effect for all these cases is affected by the blood perfusion rate,which is also investigated deeply in this study.The results demonstrate that the proposed method can be used to effectively reconstruct the concentration distribution from MPI images,and that the weighted LSM considering a quartic polynomial for interpolation provides the best results with respect to other cases considered.Furthermore,the results show that the uniformity of MNP distribution has a positive correlation with both therapeutic temperature distribution and thermal damage degree for the same dose and a critical power dissipation value in the MNPs.The MNPs uniformity inside biological tissue can be improved by the diffusion behavior after the nanofluid injection,which can ultimately reflect as an improvement of treatment effect.In addition,the blood perfusion rate considering local temperature can have a positive effect on the treatment compared to the case which considers a constant value during magnetic hyperthermia.展开更多
[Objective]This paper was to investigate the action targets and pathways of tea polyphenols in alleviating heat stress-induced injury by using network pharmacological analysis and an H9C2 cell model.[Method]First,the ...[Objective]This paper was to investigate the action targets and pathways of tea polyphenols in alleviating heat stress-induced injury by using network pharmacological analysis and an H9C2 cell model.[Method]First,the corresponding targets of tea polyphenols were obtained from the PubChem database.Then,the core targets were screened based on topological parameters.The relevant metabolism pathways of tea polyphenols related to diseases were identified through GO functional annotation and KECG signaling pathway enrichment.Moreover,common targets for thermal injury and targets of tea polyphenols were obtained.Then,GO functional annotation was performed to explore the pathway of tea polyphenols in alleviating heat stress damage.H9C2 cells were cultured at 42℃ to construct the heat stress model,and the cells were treated with 10μg/mL tea polyphenols.The key genes were confirmed using RT-PCR technology.[Result]The study yielded 364 targets corresponding to tea polyphenols,including 68 core targets.These targets are related to various biological processes such as involve oxidative stress,cancer,lipopolysaccharide-mediated signaling pathways,antiviral responses,regulation of cellular response to heat,apoptosis,and cellular lipid metabolic metabolism.Tea polyphe nols alleviate thermal damage by targeting BCL2,HSP90AA1,HSPA1A,JUN,MAPK1,NFKB1,NFKBIA,NOS3,and TP53.Moreover,10 mg/L tea polyphenols were found to upregulate the transcription levels of Hsp70,HO-1,NQ-O1,Nrf2,and MAPKI,and the transcription levels of Bax/Bcl2,p38,and JNK were downregulated to alleviate the heat stress-induced injury.[Conclusion]Tea polyphenols may enhance the antioxidant ability of H9C2 cells and inhibit cell apoptosis,thereby reducing heat stress injury.展开更多
Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens un...Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens under varying temperature and cycle conditions,employing acoustic emission monitoring,digital image correlation,and three-dimensional scanning technology.A systematic analysis was conducted on the patterns of damage evolution,failure precursor,and response mechanisms under combined thermal and cyclic loading.Experimental results show that both P-wave velocity and tensile strength degrade significantly with increasing temperature and cycle count,with temperature having a more pronounced effect than cycle count.Notably,damage evolution exhibits a dual-threshold behavior in which degradation accelerates markedly above 400℃ and stabilizes after 5 thermal cycles.Fracture surfaces evolve from initially planar to rugged morphologies,with peak-valley height differences at 600℃ being approximately three times greater than those at 200℃.Furthermore,based on acoustic emission energy entropy analysis,we introduce a novel failure precursor indicator where the sustained increase and critical surge in average entropy serve as reliable early-warning signals for impending rock failure.These findings establish a solid theoretical basis and practical methodology for damage assessment and instability early-warning systems in high-temperature rock engineering.展开更多
High temperature and high stress are critical challenges facing enhanced geothermal systems(EGS).This study investigates the physical and mechanical behavior and acoustic emission(AE)characteristics of granite subject...High temperature and high stress are critical challenges facing enhanced geothermal systems(EGS).This study investigates the physical and mechanical behavior and acoustic emission(AE)characteristics of granite subjected to heating–water cooling treatments at temperatures ranging from 25℃ to 400℃.Changes in physical properties,including volume expansion,mass loss,and P-wave velocity,were examined to quantify the extent of thermal damage.Results show that visible surface cracking occurs on granite samples treated above 300℃,with P-wave velocity being the most sensitive indicator of thermal damage.Uniaxial and triaxial compression tests were conducted to explore the effects of temperature and confining pressure on granite’s strength,deformation,failure modes,energy evolution,and brittleness.While peak strength remains largely unaffected by temperature,failure modes transition from axial splitting to shear as confining pressure increases.Thermal damage reduces the rock’s energy storage capacity and increases energy dissipation during loading.The brittleness index decreases with temperature and confining pressure,though granite still exhibits pronounced brittle behavior within the studied range.Distinct differences were observed in the AE temporal characteristics and energy evolution of granite samples under uniaxial and triaxial compression conditions.As the specimen approaches failure,the abrupt increase in AE hit rate occurs earlier than the corresponding rise in AE energy.The global b-value of the granite samples increased with treatment temperature,and the global b-value in triaxial compression tests was higher than that in uniaxial compression tests.The evolution of timedependent b-value also varied with increasing confining pressure.These findings,particularly the AE temporal characteristics and distinct b-value evolution under confinement of thermally damaged granite,provide important implications for microseismic-based stability assessment and early warning in thermally damaged rock masses.展开更多
Nickel-based superalloy(GH4169)is an ideal material for preparing turbine blades.Profile grinding of the fir-treeshaped turbine blade root can easily cause thermal damage to the workpiece specimen.This study aims to e...Nickel-based superalloy(GH4169)is an ideal material for preparing turbine blades.Profile grinding of the fir-treeshaped turbine blade root can easily cause thermal damage to the workpiece specimen.This study aims to enhance the suppression of alloy thermal damage by regulating the thickness of the oxide film on the cubic boron nitride(CBN)grinding wheel during the electrolytic in-process dressing(ELID)-assisted grinding process.A theoretical model for calculating the thickness of oxide film in ELID-assisted grinding was developed.Finite element simulation was conducted using the electrolytic film-forming process of the grinding wheel.The effects of electrical/nonelectrical parameters on the oxide film characteristics and grinding responses were addressed.The optimal matching scheme of process parameters was established.The results showed that the film layer of the grinding wheel at the blade root cam is more seriously damaged,and the workpiece surface is rougher.Further optimization of the electrode is demanded to achieve different dressing effects at various positions of the grinding wheel based on the workpiece profile.By reducing the interelectrode gap(h_(e)),increasing the power supply voltage(E_(o)),and controlling the electrolysis time(△t)at 10-15 min,the preferred film-forming efficiency and grinding quality can be achieved.By increasing the grinding wheel speed(V_(s))or decreasing the workpiece feed rate(V_(f))and grinding depth(a_(p)),the grinding thermal damage can be suppressed.A larger value of V_(f)or apcan be selected to acquire a compromise between grinding quality and film-forming efficiency after increasing the value of Vs.The optimal combination of electrical and nonelectrical parameters during this test is E_(o)=120 V,△t=15 min,h_(e)=0.1 mm,V_f=50 mm min^(-1),V_s=30 m s^(-1),and a_(p)=0.4 mm.展开更多
The kinetic energy of the ejected fragments is an effective index for quantitatively evaluating the failure severity of rockburst.To improve the measurement accuracy of the kinetic energy,the total kinetic energy was ...The kinetic energy of the ejected fragments is an effective index for quantitatively evaluating the failure severity of rockburst.To improve the measurement accuracy of the kinetic energy,the total kinetic energy was divided into translational and rotational kinetic energy in this paper.An analysis method for translational and rotational kinetic energy was subsequently proposed by introducing a four-eye high-speed photography system.Moreover,the true triaxial rockburst experiments on granite samples after heat treatment at various temperatures were carried out to reveal the evolution characteristics of the kinetic energy of rockburst.The experimental results reveal that with increasing the particle size of the rockburst fragment,the correction coefficient of measurement error of the translational kinetic energy increases first but then decreases.A power function law is obtained between the ratio of the rotational kinetic energy to the translational kinetic energy and the particle size of the rockburst fragment.Compared to the uncorrected kinetic energy measured by the system,the total kinetic energy presents a decreasing trend.The maximum proportion of total kinetic energy to uncorrected kinetic energy is 0.9.The peak stress,failure intensity and total kinetic energy all initially increase but subsequently decrease as the heat treatment temperature increases.The research outcome is favourable to revealing the impact of initial thermal damage on the rockburst mechanism.展开更多
The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical sim...The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical simulation employing a grain-based model,and the impact of initial cracks on thermal-induced strengthening is also examined by integrating random cracks within the model before tests.The results revealed that thermal stress,induced by the mismatch in thermal expansion coefficient between various minerals,is the primary distinction between rock specimens in real-time high temperature and thermal treatment.With increasing temperature,the thermal stress gradually accumulates in quartz minerals under real-time high temperature but releases after thermal treatment.The high local contact force significantly affects the peak stress and crack evolution.Uniaxial compression simulation results demonstrate that progressive accumulation of thermal stress induces degradation in macroscopic peak strength and increase of microcrack density.The grain size controls the ratio of intergranular contacts to intragranular contacts,and leads to an increase in strong contact number in the intragrain and a decrease in strong contact number in the intergrain.The strengthening of uniaxial compression strength in the experiment can be well simulated by controlling the number of pre-existing initial cracks in the numerical model.Our conclusions are beneficial to a better understanding of the underlying mechanisms of thermal damage and thermal strengthening of granite for deep geological engineering.展开更多
This research employs micro-CT scanning technology to analyze the porosity,pore fractal dimension,and spatial variability of sandstone preheated to 600℃ and subsequently cooled in water at varying temperatures(20℃,6...This research employs micro-CT scanning technology to analyze the porosity,pore fractal dimension,and spatial variability of sandstone preheated to 600℃ and subsequently cooled in water at varying temperatures(20℃,60℃,100℃).The study investigates the mechanisms by which various factors influence thermal shock damage,focusing on the effects of cooling water temperature and the boiling phase transition.The objective is to develop a method for characterizing thermal shock damage that considers spatial variability.The findings indicate that thermal shock damage is limited to a shallow depth beneath the surface,with increased severity near the surface.The boiling phase transition significantly enhances the convective heat transfer coefficient,resulting in substantially higher thermal shock damage when cooled with 100℃ boiling water compared to 20℃ and 60℃ water.Furthermore,for the entire specimen,heating damage exceeds thermal shock damage,and the influence of thermal shock diminishes as specimen size increases.This study addresses the limitations of traditional methods for assessing thermal shock damage that disregard spatial variability and provides practical guidance for engineering projects to manage thermal shock damage more effectively.展开更多
The influence of thermal damage on macroscopic and microscopic characteristics of different rocks has received much attention in the field of rock engineering.When the rocks are subjected to thermal treatment,the chan...The influence of thermal damage on macroscopic and microscopic characteristics of different rocks has received much attention in the field of rock engineering.When the rocks are subjected to thermal treatment,the change of macroscopic characteristics and evolution of micro-structure would be induced,ultimately resulting in different degrees of thermal damage in rocks.To better understand the thermal damage mechanism of different rocks and its effect on the rock performance,this study reviews a large number of test results of rock specimens experiencing heating and cooling treatment in the laboratory.Firstly,the variations of macroscopic behaviors,including physical parameters,mechanical parameters,thermal conductivity and permeability,are examined.The variations of mechanical parameters with thermal treatment variables(i.e.temperature or the number of thermal cycles)are divided into four types.Secondly,several measuring methods for microstructure,such as polarizing microscopy,fluorescent method,scanning electron microscopy(SEM),X-ray computerized tomography(CT),acoustic emission(AE)and ultrasonic technique,are introduced.Furthermore,the effect of thermal damage on the mechanical parameters of rocks in response to different thermal treatments,involving temperature magnitude,cooling method and thermal cycle,are discussed.Finally,the limitations and prospects for the research of rock thermal damage are proposed.展开更多
The roughness of the fracture surface directly affects the strength,deformation,and permeability of the surrounding rock in deep underground engineering.Understanding the effect of high temperature and thermal cycle o...The roughness of the fracture surface directly affects the strength,deformation,and permeability of the surrounding rock in deep underground engineering.Understanding the effect of high temperature and thermal cycle on the fracture surface roughness plays an important role in estimating the damage degree and stability of deep rock mass.In this paper,the variations of fracture surface roughness of granite after different heating and thermal cycles were investigated using the joint roughness coefficient method(JRC),three-dimensional(3D)roughness parameters,and fractal dimension(D),and the mechanism of damage and deterioration of granite were revealed.The experimental results show an increase in the roughness of the granite fracture surface as temperature and cycle number were incremented.The variations of JRC,height parameter,inclination parameter and area parameter with the temperature conformed to the Boltzmann's functional distribution,while the D decreased linearly as the temperature increased.Besides,the anisotropy index(Ip)of the granite fracture surface increased as the temperature increased,and the larger parameter values of roughness characterization at different temperatures were attained mainly in directions of 20°–40°,60°–100°and 140°–160°.The fracture aperture of granite after fracture followed the Gauss distribution and the average aperture increased with increasing temperature,which increased from 0.665 mm at 25℃to 1.058 mm at 800℃.High temperature caused an uneven thermal expansion,water evaporation,and oxidation of minerals within the granite,which promoted the growth and expansion of microfractures,and reduced interparticle bonding strength.In particular,the damage was exacerbated by the expansion and cracking of the quartz phase transition after T>500℃.Thermal cycles contributed to the accumulation of this damage and further weakened the interparticle bonding forces,resulting in a significant increase in the roughness,anisotropy,and aperture of the fracture surface after five cycles.展开更多
In this study,we attempted to investigate the spatial gradient distributions of thermal shock-induced damage to granite with respect to associated deterioration mechanisms.First,thermal shock experiments were conducte...In this study,we attempted to investigate the spatial gradient distributions of thermal shock-induced damage to granite with respect to associated deterioration mechanisms.First,thermal shock experiments were conducted on granite specimens by slowly preheating the specimens to high temperatures,followed by rapid cooling in tap water.Then,the spatial gradient distributions of thermal shock-induced damage were investigated by computed tomography(CT)and image analysis techniques.Finally,the influence of the preheating temperature on the spatial gradients of the damage was discussed.The results show that the thermal shock induced by rapid cooling can cause more damage to granite than that induced by slow cooling.The thermal shock induced by rapid cooling can cause spatial gradient distributions of the damage to granite.The damage near the specimen surface was at a maximum,while the damage inside the specimen was at a minimum.In addition,the preheating temperature can significantly influence the spatial gradient distributions of the thermal shock-induced damage.The spatial gradient distribution of damage increased as the preheating temperature increased and then decreased significantly over 600C.When the preheating temperature was sufficiently high(e.g.800C),the gradient can be ignored.展开更多
Clay swelling and fines migration pose significant challenges to thermally enhanced oil recovery(EOR)operations,particularly in clay-rich formations.This study systematically investigates clay swelling behavior and pe...Clay swelling and fines migration pose significant challenges to thermally enhanced oil recovery(EOR)operations,particularly in clay-rich formations.This study systematically investigates clay swelling behavior and permeability impairment under high-temperature,low-salinity(HTLS) conditions and evaluates various inhibition methods to mitigate formation damage.To ensure realistic analysis,data and materials from a field with similar issues in Kazakhstan were used.Static/dynamic swelling tests demonstrated that a quaternary ammonium-based inhibitor consistently provided superior clay stabilization through effective ion exchange and surface charge modification mechanisms.In distilled water at 100℃,inhibitor-treated samples maintained 48.89 % of their original permeability,while untreated samples exhibited severe damage,retaining only 17.05 %.Additionally,this chemical inhibitor significantly lowered the critical salt concentration(CSC),effectively stabilizing clay at 4920 ppm salinity compared to 7380 ppm required without treatment.Scanning electron microscopy(SEM) imaging corroborated these results,revealing that inhibitor-treated clay maintains a compact and coherent structure,in stark contrast to the pronounced swelling,delamination,and structural deterioration observed in untreated clay samples.Nevertheless,this quaternary ammonium-based clay stabilizer presents a robust and promising solution for reducing clay swelling-induced damage,sustaining reservoir permeability,and improving thermal EOR performance in swelling-prone formations.展开更多
A comprehensive model is proposed to evaluate the damage capability of laser system in ground-air defense environments.This model takes into account the laser system's heavy reliance on weather conditions and the ...A comprehensive model is proposed to evaluate the damage capability of laser system in ground-air defense environments.This model takes into account the laser system's heavy reliance on weather conditions and the stringent requirements for beam pointing accuracy.It initiates by simulating the laser spot characteristics on target in ground-to-air environments,factoring in the effects of atmospheric turbulence,absorption and scattering through slant transmission paths.Subsequently,a calculation method based on the thermal damage effect of the target material is introduced to quantify the damage ability of the laser system.To further enhance the model's applicability,a method for calculating the laser damage probability based on random crossover theory has been introduced,which takes into account the error of the Acquisition,Tracking and Pointing(ATP)system to estimate the likelihood of successful damage in operation applications.Theoretical analysis and simulation results validate the effectiveness of the proposed model in calculating and analyzing the damage capability of laser system in ground-air defense environments.This model offers valuable decision-making insights for users of laser systems operating in lowaltitude atmospheric conditions.Furthermore,it furnishes essential data support for the development and validation of laser systems,ensuring their effectiveness in real-world applications.展开更多
The emergence of laser technology has led to the gradual integration of laser weapon system(LaWS)into military scene,particularly in the field of anti-unmanned aerial vehicle(UAV),showcasing significant potential.Howe...The emergence of laser technology has led to the gradual integration of laser weapon system(LaWS)into military scene,particularly in the field of anti-unmanned aerial vehicle(UAV),showcasing significant potential.However,A current limitation lies in the absence of a comprehensive quantitative approach to assess the capabilities of LaWS.To address this issue,a damage effectiveness characterization model for LaWS is established,taking into account the properties of laser transmission through the atmosphere and the thermal damage effects.By employing this model,key parameters pertaining to the effectiveness of laser damage are determined.The impact of various spatial positions and atmospheric conditions on the damage effectiveness of LaWS have been examined,employing simulation experiments with diverse parameters.The conclusions indicate that the damage effectiveness of LaWS is contingent upon the spatial position of the target,resulting in a diminished effectiveness to damage on distant,low-altitude targets.Additionally,the damage effectiveness of LaWS is heavily reliant on the atmospheric condition,particularly in complex settings such as midday and low visibility conditions,where the damage effectiveness is substantially reduced.This paper provides an accurate and effective calculation method for the rapid decisionmaking of the operators.展开更多
To investigate the specific creep behavior of ultra-deep buried salt during oil and gas exploitation,a set of triaxial creep experiments was conducted at elevated temperatures with constant axial pressure and unloadin...To investigate the specific creep behavior of ultra-deep buried salt during oil and gas exploitation,a set of triaxial creep experiments was conducted at elevated temperatures with constant axial pressure and unloading confining pressure conditions.Experimental results show that the salt sample deforms more significantly with the increase of applied temperature and deviatoric loading.The accelerated creep phase is not occurring until the applied temperature reaches 130℃,and higher temperature is beneficial to the occurrence of accelerated creep.To describe the specific creep behavior,a novel three-dimensional(3D)creep constitutive model is developed that incorporates the thermal and mechanical variables into mechanical elements.Subsequently,the standard particle swarm optimization(SPSO)method is adopted to fit the experimental data,and the sensibility of key model parameters is analyzed to further illustrate the model function.As a result,the model can accurately predict the creep behavior of salt under the coupled thermo-mechanical effect in deep-buried condition.Based on the research results,the creep mechanical behavior of wellbore shrinkage is predicted in deep drilling projects crossing salt layer,which has practical implications for deep rock mechanics problems.展开更多
An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microst...An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microstructure evolution and properties of magnesia–spinel refractories were characterized by the high-temperature elastic modulus,thermal shock damage resistance parameters,retainment of elastic modulus after thermal shock,and scanning electron microscopy.The results indicated that the incorporation of calcia-stabilized zirconia improved the thermomechanical properties and thermal shock behavior of magnesia–spinel specimens.The hot modulus of rupture of magnesia–spinel specimens increased by 2.5-fold due to the incorporation of calcia-stabilized zirconia micro-powder.The presence of a martensitic phase transformation in partially unstable ZrO2 and thermal mismatches among various phases contributed to a controlled formation of microcracks.And the pinning effect caused by the calcia-stabilized zirconia particles surrounding the grain boundaries played a crucial role in preventing the propagation of microcracks.This phenomenon significantly bolstered the thermal shock stability of magnesia–spinel refractories,consequently prolonging their service life.展开更多
Underground rock dynamic disasters are becoming more severe due to the increasing depth of human operations underground.Underground temperature and pressure conditions contribute significantly to these disasters.There...Underground rock dynamic disasters are becoming more severe due to the increasing depth of human operations underground.Underground temperature and pressure conditions contribute significantly to these disasters.Therefore,it is important to understand the coupled thermo-mechanical(TM)behaviour of rocks for the long-term safety and maintenance of underground tunnelling and mining.Moreover,investigation of the damage,strength and failure characteristics of rocks under triaxial stress conditions is important to avoid underground rock disasters.In this study,based on Weibull distribution and Lemaitre's strain equivalent principle,a statistical coupled TM constitutive model for sandstone was established under high temperature and pressure conditions.The triaxial test results of sandstone under different temperature and pressure conditions were used to validate the model.The proposed model was in good agreement with the experimental results up to 600℃.The total TM damage was decreased with increasing temperature,while it was increased with increasing confining pressure.The model's parameters can be calculated using conventional laboratory test results.展开更多
基金support from the National Natural Science Foundation of China under Grant No.51879135supported by the Taishan Scholars Program(Grant No.ZR2021ME099)the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Grant No.SKLGME023003。
文摘Understanding how thermal damage accumulates in granites under cyclic thermal loading is crucial for geoengineering design and stability assessment.Two types of granite with different grain sizes were subjected to multiple heating and cooling cycles at identical or increasing target temperatures using a new apparatus.Acoustic emission(AE)and thermal deformation were monitored simultaneously.Ultrasonic velocity,porosity,and permeability measurements,compression tests,and thin-section petrography were conducted to assess the thermal damage and physical and mechanical properties of the treated specimens.The results indicate that the thermal damage progression exhibits cycle-dependent decay at 300℃,and the thermal deformation tends to be elastic.However,the uniaxial compressive strength(UCS)increases after thermal treatment,though the increment decreases with progressive cycles(from 21%to 4%for coarse-grained granite).Progressive temperature cycling induces cumulative damage amplification,manifested by tremendous thermal cracking(the total number of AE hits reaches-170 and 180 times that of the first cycle)and crack density escalation(the crack density reaches-1.6 and 2 times that of the first cycle).AE results reveal that there is a temperature-memory effect in both rock types,and show that thermal stresses are insufficient to generate new thermal damage until the prior exposed temperature is exceeded.Additionally,thermal damage is related to the microstructure of rock:coarse-grained granite with more pre-existing cracks exhibits heating-dominated damage(e.g.94%of the AE energy was generated during heating at 300℃),while fine-grained granite with less inherent damage is more sensitive to cooling(e.g.71%of the AE energy was generated during cooling).Quantitative relationship among P-wave velocity,Young's modulus,and linear crack density provide a good estimation of thermal damage,and can guide assessments of the durability of underground engineering.
基金supported by the National Natural Science Foundation of China(Nos.51104128,51322401,51304201 and 51204159)Jiangsu Province Prospective industry-UniversityResearch Cooperation Research Program of China(No.BY2012085)+2 种基金Doctor Station Fund of China(No.20120095110013)333 Project Program of Jiangsu Province of China"Blue Project" Program of Jiangsu Province of China
文摘The uniaxial compression tests for mudstone specimens are carried out with four different loading rates from room temperature to 400℃ by using the Rock Mechanics Servo-controlled Testing System MTS810 and high temperature furnace MTS652.02.The mechanical properties of mudstone with various loading rates are studied under different temperature conditions.The results show that when temperature increases from room temperature to 400℃ and loading rate is less than 0.03 mm/s,the peak strength of mudstone specimen decreases as loading rate increases,while the various peak strengths show significant differences when loading rate exceeds 0.03 mm/s.At room temperature,the elastic modulus decreases at the first time and then increases with loading rate rising.When the temperature is between200 and 400℃,the elastic modulus presents a decreasing trend with increasing loading rate.With increasing the loading rate,the number of fragments in mudstone becomes larger and even the powder is observed in mudstone with higher loading rate.Under high loading rate,the failure mode of mudstone specimens under different temperatures is mainly conical damage.
基金This work was supported by the Overseas Research Studentship(ORS)Overseas Trust Scholarship of Cambridge Uni-versity,the National Natural Science Foundation of China(10328203,10572111,10632060)+1 种基金the National 111 Project of China(B06024)the National Basic Research Program of China(2006CB601202)
文摘Skin thermal damage or skin burns are the most commonly encountered type of trauma in civilian and military communities. Besides, advances in laser, microwave and similar technologies have led to recent developments of thermal treatments for disease and damage involving skin tissue, where the objective is to induce thermal damage precisely within targeted tissue structures but without affecting the surrounding, healthy tissue. Further, extended pain sensation induced by thermal damage has also brought great problem for burn patients. Thus, it is of great importance to quantify the thermal damage in skin tissue. In this paper, the available models and experimental methods for quantification of thermal damage in skin tissue are discussed.
文摘Magnetic particle imaging(MPI)technology can generate a real-time magnetic nanoparticle(MNP)distribution image for biological tissues,and its use can overcome the limitations imposed in magnetic hyperthermia treatments by the unpredictable MNP distribution after the intratumoral injection of nanofluid.However,the MNP concentration distribution is generally difficult to be extracted from MPI images.This study proposes an approach to extract the corresponding concentration value of each pixel from an MPI image by a least squares method(LSM),which is then translated as MNP concentration distribution by an interpolation function.The resulting MPI-based concentration distribution is used to evaluate the treatment effect and the results are compared with the ones of two baseline cases under the same dose:uniform distribution and MPI-based distribution considering diffusion.Additionally,the treatment effect for all these cases is affected by the blood perfusion rate,which is also investigated deeply in this study.The results demonstrate that the proposed method can be used to effectively reconstruct the concentration distribution from MPI images,and that the weighted LSM considering a quartic polynomial for interpolation provides the best results with respect to other cases considered.Furthermore,the results show that the uniformity of MNP distribution has a positive correlation with both therapeutic temperature distribution and thermal damage degree for the same dose and a critical power dissipation value in the MNPs.The MNPs uniformity inside biological tissue can be improved by the diffusion behavior after the nanofluid injection,which can ultimately reflect as an improvement of treatment effect.In addition,the blood perfusion rate considering local temperature can have a positive effect on the treatment compared to the case which considers a constant value during magnetic hyperthermia.
基金Supported by National Natural Science Foundation of China(32302919,32302918)Taishan Industrial Experts Program(tscx202306046)+1 种基金Key R&D Program Rural Revitalization Project of Shandong Province(2023TZXD083)Science and Technology Cooperation Project of Shandong and Chongqing(2022LYXZ030)。
文摘[Objective]This paper was to investigate the action targets and pathways of tea polyphenols in alleviating heat stress-induced injury by using network pharmacological analysis and an H9C2 cell model.[Method]First,the corresponding targets of tea polyphenols were obtained from the PubChem database.Then,the core targets were screened based on topological parameters.The relevant metabolism pathways of tea polyphenols related to diseases were identified through GO functional annotation and KECG signaling pathway enrichment.Moreover,common targets for thermal injury and targets of tea polyphenols were obtained.Then,GO functional annotation was performed to explore the pathway of tea polyphenols in alleviating heat stress damage.H9C2 cells were cultured at 42℃ to construct the heat stress model,and the cells were treated with 10μg/mL tea polyphenols.The key genes were confirmed using RT-PCR technology.[Result]The study yielded 364 targets corresponding to tea polyphenols,including 68 core targets.These targets are related to various biological processes such as involve oxidative stress,cancer,lipopolysaccharide-mediated signaling pathways,antiviral responses,regulation of cellular response to heat,apoptosis,and cellular lipid metabolic metabolism.Tea polyphe nols alleviate thermal damage by targeting BCL2,HSP90AA1,HSPA1A,JUN,MAPK1,NFKB1,NFKBIA,NOS3,and TP53.Moreover,10 mg/L tea polyphenols were found to upregulate the transcription levels of Hsp70,HO-1,NQ-O1,Nrf2,and MAPKI,and the transcription levels of Bax/Bcl2,p38,and JNK were downregulated to alleviate the heat stress-induced injury.[Conclusion]Tea polyphenols may enhance the antioxidant ability of H9C2 cells and inhibit cell apoptosis,thereby reducing heat stress injury.
基金supported by National Natural Science Foundation of China (Nos.52264006,52364004,and 52464005)the Guizhou Provincial Science and Technology Foundation (No.GCC[2022]005-1)。
文摘Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens under varying temperature and cycle conditions,employing acoustic emission monitoring,digital image correlation,and three-dimensional scanning technology.A systematic analysis was conducted on the patterns of damage evolution,failure precursor,and response mechanisms under combined thermal and cyclic loading.Experimental results show that both P-wave velocity and tensile strength degrade significantly with increasing temperature and cycle count,with temperature having a more pronounced effect than cycle count.Notably,damage evolution exhibits a dual-threshold behavior in which degradation accelerates markedly above 400℃ and stabilizes after 5 thermal cycles.Fracture surfaces evolve from initially planar to rugged morphologies,with peak-valley height differences at 600℃ being approximately three times greater than those at 200℃.Furthermore,based on acoustic emission energy entropy analysis,we introduce a novel failure precursor indicator where the sustained increase and critical surge in average entropy serve as reliable early-warning signals for impending rock failure.These findings establish a solid theoretical basis and practical methodology for damage assessment and instability early-warning systems in high-temperature rock engineering.
基金supported by the CHN Energy Investment Group,grant numbers GJNY-23-86 and GJNY-23-92.
文摘High temperature and high stress are critical challenges facing enhanced geothermal systems(EGS).This study investigates the physical and mechanical behavior and acoustic emission(AE)characteristics of granite subjected to heating–water cooling treatments at temperatures ranging from 25℃ to 400℃.Changes in physical properties,including volume expansion,mass loss,and P-wave velocity,were examined to quantify the extent of thermal damage.Results show that visible surface cracking occurs on granite samples treated above 300℃,with P-wave velocity being the most sensitive indicator of thermal damage.Uniaxial and triaxial compression tests were conducted to explore the effects of temperature and confining pressure on granite’s strength,deformation,failure modes,energy evolution,and brittleness.While peak strength remains largely unaffected by temperature,failure modes transition from axial splitting to shear as confining pressure increases.Thermal damage reduces the rock’s energy storage capacity and increases energy dissipation during loading.The brittleness index decreases with temperature and confining pressure,though granite still exhibits pronounced brittle behavior within the studied range.Distinct differences were observed in the AE temporal characteristics and energy evolution of granite samples under uniaxial and triaxial compression conditions.As the specimen approaches failure,the abrupt increase in AE hit rate occurs earlier than the corresponding rise in AE energy.The global b-value of the granite samples increased with treatment temperature,and the global b-value in triaxial compression tests was higher than that in uniaxial compression tests.The evolution of timedependent b-value also varied with increasing confining pressure.These findings,particularly the AE temporal characteristics and distinct b-value evolution under confinement of thermally damaged granite,provide important implications for microseismic-based stability assessment and early warning in thermally damaged rock masses.
基金supported by the Shanghai“Explorer Program”Project(Grant No.24TS1414500)the 10th Sino-Hungarian Intergovernmental Scientific and Technological Cooperation Project(Grant No.2024-10-2)。
文摘Nickel-based superalloy(GH4169)is an ideal material for preparing turbine blades.Profile grinding of the fir-treeshaped turbine blade root can easily cause thermal damage to the workpiece specimen.This study aims to enhance the suppression of alloy thermal damage by regulating the thickness of the oxide film on the cubic boron nitride(CBN)grinding wheel during the electrolytic in-process dressing(ELID)-assisted grinding process.A theoretical model for calculating the thickness of oxide film in ELID-assisted grinding was developed.Finite element simulation was conducted using the electrolytic film-forming process of the grinding wheel.The effects of electrical/nonelectrical parameters on the oxide film characteristics and grinding responses were addressed.The optimal matching scheme of process parameters was established.The results showed that the film layer of the grinding wheel at the blade root cam is more seriously damaged,and the workpiece surface is rougher.Further optimization of the electrode is demanded to achieve different dressing effects at various positions of the grinding wheel based on the workpiece profile.By reducing the interelectrode gap(h_(e)),increasing the power supply voltage(E_(o)),and controlling the electrolysis time(△t)at 10-15 min,the preferred film-forming efficiency and grinding quality can be achieved.By increasing the grinding wheel speed(V_(s))or decreasing the workpiece feed rate(V_(f))and grinding depth(a_(p)),the grinding thermal damage can be suppressed.A larger value of V_(f)or apcan be selected to acquire a compromise between grinding quality and film-forming efficiency after increasing the value of Vs.The optimal combination of electrical and nonelectrical parameters during this test is E_(o)=120 V,△t=15 min,h_(e)=0.1 mm,V_f=50 mm min^(-1),V_s=30 m s^(-1),and a_(p)=0.4 mm.
基金supported by the National Natural Science Foundation of China(Grant Nos.41572334,41941018)the Fundamental Research Funds for the Central Universities(Ph.D.Top Innovative Talents Fund of CUMTB)(Grant No.BBJ2024078)。
文摘The kinetic energy of the ejected fragments is an effective index for quantitatively evaluating the failure severity of rockburst.To improve the measurement accuracy of the kinetic energy,the total kinetic energy was divided into translational and rotational kinetic energy in this paper.An analysis method for translational and rotational kinetic energy was subsequently proposed by introducing a four-eye high-speed photography system.Moreover,the true triaxial rockburst experiments on granite samples after heat treatment at various temperatures were carried out to reveal the evolution characteristics of the kinetic energy of rockburst.The experimental results reveal that with increasing the particle size of the rockburst fragment,the correction coefficient of measurement error of the translational kinetic energy increases first but then decreases.A power function law is obtained between the ratio of the rotational kinetic energy to the translational kinetic energy and the particle size of the rockburst fragment.Compared to the uncorrected kinetic energy measured by the system,the total kinetic energy presents a decreasing trend.The maximum proportion of total kinetic energy to uncorrected kinetic energy is 0.9.The peak stress,failure intensity and total kinetic energy all initially increase but subsequently decrease as the heat treatment temperature increases.The research outcome is favourable to revealing the impact of initial thermal damage on the rockburst mechanism.
基金Project(51879135)supported by the Taishan Scholars Program,ChinaProject(52309130)supported by the National Natural Science Foundation of China+1 种基金Project(SKLGME023003)supported by the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,ChinaProject(2022AH051754)supported by the Natural Science Research Project of Anhui Universities,China。
文摘The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical simulation employing a grain-based model,and the impact of initial cracks on thermal-induced strengthening is also examined by integrating random cracks within the model before tests.The results revealed that thermal stress,induced by the mismatch in thermal expansion coefficient between various minerals,is the primary distinction between rock specimens in real-time high temperature and thermal treatment.With increasing temperature,the thermal stress gradually accumulates in quartz minerals under real-time high temperature but releases after thermal treatment.The high local contact force significantly affects the peak stress and crack evolution.Uniaxial compression simulation results demonstrate that progressive accumulation of thermal stress induces degradation in macroscopic peak strength and increase of microcrack density.The grain size controls the ratio of intergranular contacts to intragranular contacts,and leads to an increase in strong contact number in the intragrain and a decrease in strong contact number in the intergrain.The strengthening of uniaxial compression strength in the experiment can be well simulated by controlling the number of pre-existing initial cracks in the numerical model.Our conclusions are beneficial to a better understanding of the underlying mechanisms of thermal damage and thermal strengthening of granite for deep geological engineering.
基金financially supported by the National Natural Science Foundation of China(Grant No.51874207)the Natural Science Foundation of Shanxi Province(Grant Nos.202303021211042 and 202303011222006).
文摘This research employs micro-CT scanning technology to analyze the porosity,pore fractal dimension,and spatial variability of sandstone preheated to 600℃ and subsequently cooled in water at varying temperatures(20℃,60℃,100℃).The study investigates the mechanisms by which various factors influence thermal shock damage,focusing on the effects of cooling water temperature and the boiling phase transition.The objective is to develop a method for characterizing thermal shock damage that considers spatial variability.The findings indicate that thermal shock damage is limited to a shallow depth beneath the surface,with increased severity near the surface.The boiling phase transition significantly enhances the convective heat transfer coefficient,resulting in substantially higher thermal shock damage when cooled with 100℃ boiling water compared to 20℃ and 60℃ water.Furthermore,for the entire specimen,heating damage exceeds thermal shock damage,and the influence of thermal shock diminishes as specimen size increases.This study addresses the limitations of traditional methods for assessing thermal shock damage that disregard spatial variability and provides practical guidance for engineering projects to manage thermal shock damage more effectively.
基金supported by the National Key Research and Development Plan(Grant No.2022YFC2905700)Natural Science Foundation of Anhui Province(Grant No.2208085ME120)Key Research and Development Plan of Anhui Province(Grant No.2022m07020001).
文摘The influence of thermal damage on macroscopic and microscopic characteristics of different rocks has received much attention in the field of rock engineering.When the rocks are subjected to thermal treatment,the change of macroscopic characteristics and evolution of micro-structure would be induced,ultimately resulting in different degrees of thermal damage in rocks.To better understand the thermal damage mechanism of different rocks and its effect on the rock performance,this study reviews a large number of test results of rock specimens experiencing heating and cooling treatment in the laboratory.Firstly,the variations of macroscopic behaviors,including physical parameters,mechanical parameters,thermal conductivity and permeability,are examined.The variations of mechanical parameters with thermal treatment variables(i.e.temperature or the number of thermal cycles)are divided into four types.Secondly,several measuring methods for microstructure,such as polarizing microscopy,fluorescent method,scanning electron microscopy(SEM),X-ray computerized tomography(CT),acoustic emission(AE)and ultrasonic technique,are introduced.Furthermore,the effect of thermal damage on the mechanical parameters of rocks in response to different thermal treatments,involving temperature magnitude,cooling method and thermal cycle,are discussed.Finally,the limitations and prospects for the research of rock thermal damage are proposed.
基金funding support from the National Natural Science Foundation of China(Grant No.52274082)the Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology(Grant No.JXUSTQJBJ2020003)the Innovation Fund Designated for Graduate Students of Jiangxi Province(Grant No.YC2023-B215).
文摘The roughness of the fracture surface directly affects the strength,deformation,and permeability of the surrounding rock in deep underground engineering.Understanding the effect of high temperature and thermal cycle on the fracture surface roughness plays an important role in estimating the damage degree and stability of deep rock mass.In this paper,the variations of fracture surface roughness of granite after different heating and thermal cycles were investigated using the joint roughness coefficient method(JRC),three-dimensional(3D)roughness parameters,and fractal dimension(D),and the mechanism of damage and deterioration of granite were revealed.The experimental results show an increase in the roughness of the granite fracture surface as temperature and cycle number were incremented.The variations of JRC,height parameter,inclination parameter and area parameter with the temperature conformed to the Boltzmann's functional distribution,while the D decreased linearly as the temperature increased.Besides,the anisotropy index(Ip)of the granite fracture surface increased as the temperature increased,and the larger parameter values of roughness characterization at different temperatures were attained mainly in directions of 20°–40°,60°–100°and 140°–160°.The fracture aperture of granite after fracture followed the Gauss distribution and the average aperture increased with increasing temperature,which increased from 0.665 mm at 25℃to 1.058 mm at 800℃.High temperature caused an uneven thermal expansion,water evaporation,and oxidation of minerals within the granite,which promoted the growth and expansion of microfractures,and reduced interparticle bonding strength.In particular,the damage was exacerbated by the expansion and cracking of the quartz phase transition after T>500℃.Thermal cycles contributed to the accumulation of this damage and further weakened the interparticle bonding forces,resulting in a significant increase in the roughness,anisotropy,and aperture of the fracture surface after five cycles.
基金funded by the National Natural Science Foundation of China,China(Grant Nos.51778021,51627812 and 51678403)。
文摘In this study,we attempted to investigate the spatial gradient distributions of thermal shock-induced damage to granite with respect to associated deterioration mechanisms.First,thermal shock experiments were conducted on granite specimens by slowly preheating the specimens to high temperatures,followed by rapid cooling in tap water.Then,the spatial gradient distributions of thermal shock-induced damage were investigated by computed tomography(CT)and image analysis techniques.Finally,the influence of the preheating temperature on the spatial gradients of the damage was discussed.The results show that the thermal shock induced by rapid cooling can cause more damage to granite than that induced by slow cooling.The thermal shock induced by rapid cooling can cause spatial gradient distributions of the damage to granite.The damage near the specimen surface was at a maximum,while the damage inside the specimen was at a minimum.In addition,the preheating temperature can significantly influence the spatial gradient distributions of the thermal shock-induced damage.The spatial gradient distribution of damage increased as the preheating temperature increased and then decreased significantly over 600C.When the preheating temperature was sufficiently high(e.g.800C),the gradient can be ignored.
文摘Clay swelling and fines migration pose significant challenges to thermally enhanced oil recovery(EOR)operations,particularly in clay-rich formations.This study systematically investigates clay swelling behavior and permeability impairment under high-temperature,low-salinity(HTLS) conditions and evaluates various inhibition methods to mitigate formation damage.To ensure realistic analysis,data and materials from a field with similar issues in Kazakhstan were used.Static/dynamic swelling tests demonstrated that a quaternary ammonium-based inhibitor consistently provided superior clay stabilization through effective ion exchange and surface charge modification mechanisms.In distilled water at 100℃,inhibitor-treated samples maintained 48.89 % of their original permeability,while untreated samples exhibited severe damage,retaining only 17.05 %.Additionally,this chemical inhibitor significantly lowered the critical salt concentration(CSC),effectively stabilizing clay at 4920 ppm salinity compared to 7380 ppm required without treatment.Scanning electron microscopy(SEM) imaging corroborated these results,revealing that inhibitor-treated clay maintains a compact and coherent structure,in stark contrast to the pronounced swelling,delamination,and structural deterioration observed in untreated clay samples.Nevertheless,this quaternary ammonium-based clay stabilizer presents a robust and promising solution for reducing clay swelling-induced damage,sustaining reservoir permeability,and improving thermal EOR performance in swelling-prone formations.
基金co-supported by the National Social Science Foundation of China(No.2022-SKJJ-C-037)the Ministerial-level Funding Project,China(JY2023A016)。
文摘A comprehensive model is proposed to evaluate the damage capability of laser system in ground-air defense environments.This model takes into account the laser system's heavy reliance on weather conditions and the stringent requirements for beam pointing accuracy.It initiates by simulating the laser spot characteristics on target in ground-to-air environments,factoring in the effects of atmospheric turbulence,absorption and scattering through slant transmission paths.Subsequently,a calculation method based on the thermal damage effect of the target material is introduced to quantify the damage ability of the laser system.To further enhance the model's applicability,a method for calculating the laser damage probability based on random crossover theory has been introduced,which takes into account the error of the Acquisition,Tracking and Pointing(ATP)system to estimate the likelihood of successful damage in operation applications.Theoretical analysis and simulation results validate the effectiveness of the proposed model in calculating and analyzing the damage capability of laser system in ground-air defense environments.This model offers valuable decision-making insights for users of laser systems operating in lowaltitude atmospheric conditions.Furthermore,it furnishes essential data support for the development and validation of laser systems,ensuring their effectiveness in real-world applications.
基金supported by the National Social Science Foundation of China(2022-SKJJ-C-037)the National Natural Science Foundation of China General Program(72071209).
文摘The emergence of laser technology has led to the gradual integration of laser weapon system(LaWS)into military scene,particularly in the field of anti-unmanned aerial vehicle(UAV),showcasing significant potential.However,A current limitation lies in the absence of a comprehensive quantitative approach to assess the capabilities of LaWS.To address this issue,a damage effectiveness characterization model for LaWS is established,taking into account the properties of laser transmission through the atmosphere and the thermal damage effects.By employing this model,key parameters pertaining to the effectiveness of laser damage are determined.The impact of various spatial positions and atmospheric conditions on the damage effectiveness of LaWS have been examined,employing simulation experiments with diverse parameters.The conclusions indicate that the damage effectiveness of LaWS is contingent upon the spatial position of the target,resulting in a diminished effectiveness to damage on distant,low-altitude targets.Additionally,the damage effectiveness of LaWS is heavily reliant on the atmospheric condition,particularly in complex settings such as midday and low visibility conditions,where the damage effectiveness is substantially reduced.This paper provides an accurate and effective calculation method for the rapid decisionmaking of the operators.
基金This research was financially supported by the Scientific and technological research projects in Sichuan province(Grant Nos.2022YFSY0007 and 2021YFH0010)the National Scientific Science Foundation of China(Grant No.U20A20266).
文摘To investigate the specific creep behavior of ultra-deep buried salt during oil and gas exploitation,a set of triaxial creep experiments was conducted at elevated temperatures with constant axial pressure and unloading confining pressure conditions.Experimental results show that the salt sample deforms more significantly with the increase of applied temperature and deviatoric loading.The accelerated creep phase is not occurring until the applied temperature reaches 130℃,and higher temperature is beneficial to the occurrence of accelerated creep.To describe the specific creep behavior,a novel three-dimensional(3D)creep constitutive model is developed that incorporates the thermal and mechanical variables into mechanical elements.Subsequently,the standard particle swarm optimization(SPSO)method is adopted to fit the experimental data,and the sensibility of key model parameters is analyzed to further illustrate the model function.As a result,the model can accurately predict the creep behavior of salt under the coupled thermo-mechanical effect in deep-buried condition.Based on the research results,the creep mechanical behavior of wellbore shrinkage is predicted in deep drilling projects crossing salt layer,which has practical implications for deep rock mechanics problems.
基金supported by the Key Project of the National Natural Science Foundation of China(Grant No.U21A2058)the Hebei Guoliang New Materials Co.,Ltd.(Grant No.22150239J).
文摘An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microstructure evolution and properties of magnesia–spinel refractories were characterized by the high-temperature elastic modulus,thermal shock damage resistance parameters,retainment of elastic modulus after thermal shock,and scanning electron microscopy.The results indicated that the incorporation of calcia-stabilized zirconia improved the thermomechanical properties and thermal shock behavior of magnesia–spinel specimens.The hot modulus of rupture of magnesia–spinel specimens increased by 2.5-fold due to the incorporation of calcia-stabilized zirconia micro-powder.The presence of a martensitic phase transformation in partially unstable ZrO2 and thermal mismatches among various phases contributed to a controlled formation of microcracks.And the pinning effect caused by the calcia-stabilized zirconia particles surrounding the grain boundaries played a crucial role in preventing the propagation of microcracks.This phenomenon significantly bolstered the thermal shock stability of magnesia–spinel refractories,consequently prolonging their service life.
基金the Bowen Basin Underground Geotechnical Society for funding this project。
文摘Underground rock dynamic disasters are becoming more severe due to the increasing depth of human operations underground.Underground temperature and pressure conditions contribute significantly to these disasters.Therefore,it is important to understand the coupled thermo-mechanical(TM)behaviour of rocks for the long-term safety and maintenance of underground tunnelling and mining.Moreover,investigation of the damage,strength and failure characteristics of rocks under triaxial stress conditions is important to avoid underground rock disasters.In this study,based on Weibull distribution and Lemaitre's strain equivalent principle,a statistical coupled TM constitutive model for sandstone was established under high temperature and pressure conditions.The triaxial test results of sandstone under different temperature and pressure conditions were used to validate the model.The proposed model was in good agreement with the experimental results up to 600℃.The total TM damage was decreased with increasing temperature,while it was increased with increasing confining pressure.The model's parameters can be calculated using conventional laboratory test results.
