Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20</span><sup><span style="font-family:Verdana;">th</span></sup><span ...Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;"> century. The facts justifying the connection are given by Siberian Fan Reliefs and the Tunguska Cosmic Body. It is most natural to assume that we are dealing with the falling of numerous fragments of a collapsed comet. The more likely version is that the comet is captured by the Earth-Moon system and remains in Earth orbit for some time.展开更多
Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20<sup>th</sup> century. These reliefs consist of several tens (up to hundreds) of stripes that have ...Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20<sup>th</sup> century. These reliefs consist of several tens (up to hundreds) of stripes that have arisen as a result of the destruction of vegetation and the surface layer of the ground. Structures of stripes are extended, ranging in size from 6 km to ≥20 km, with a width of several kilometers. Every strip (scratch on the ground) is roughly estimated to be up to 50 m wide and ≥500 m long. The stripes start from one edge of the relief and stretch at inter-vals to the other, slightly diverging symmetrically from the central axis. It was determined that these reliefs are not associated with the movement of soil (avalanches, mudflows) or with the impact of air currents (hurricanes, storm, tornado). Geographically, these struc-tures of stripes are located within a circle with a radius of 770 km, described around the epicenter of the Tunguska catastrophe.展开更多
Giant wooden reliefsillustrate some 45 ancientChinese myths, reflectingthe wisdom of the Chinesenation in antiquity. Eachboard depicts a legendaryscene, enabling viewers tovisualise the nature of theChinese nation and...Giant wooden reliefsillustrate some 45 ancientChinese myths, reflectingthe wisdom of the Chinesenation in antiquity. Eachboard depicts a legendaryscene, enabling viewers tovisualise the nature of theChinese nation and thespirit of the ancient country.展开更多
As service conditions become more challenging and production complexity increases,there is an increasing demand for enhanced comprehensive performance of ceramic/metal heterostructures.At present,brazing technique has...As service conditions become more challenging and production complexity increases,there is an increasing demand for enhanced comprehensive performance of ceramic/metal heterostructures.At present,brazing technique has been widely utilized for ceramic-metal heterogeneous joints.However,the residual stress relief in these welding joints is complicated and necessary.Because metals and ceramics have different properties,especially their coefficients of thermal expansion.Welding joints exhibit large residual stresses during the cooling process.The relatively high residual stresses may significantly degrade the joint properties.For this issue,four alleviation routes were reviewed:optimization of process parameters,setting an intermediate layer,surface structure modulation and particle-reinforced composite solder.The states and distribution patterns of residual stress in ceramic-metal brazed joints were summarized,and the generation and detection of residual stress were introduced.Eventually,upcoming prospects and challenges of residual stress research on ceramic/metal heterostructures were pointed out.展开更多
After the earthquake struck Myanmar on March 28th,China NGO Network for International Exchanges(CNIE)immediately contacted the emergency management department for the registration process of non-governmental rescue fo...After the earthquake struck Myanmar on March 28th,China NGO Network for International Exchanges(CNIE)immediately contacted the emergency management department for the registration process of non-governmental rescue forces participating in earthquake relief work and guided its member organisations and partners to orderly participate in the disaster relief.展开更多
Rainfall-induced landslides are often highly destructive.Reviewing and analyzing the causes,processes,impacts,and deficiencies in emergency response is critical for improving disaster prevention and management.From th...Rainfall-induced landslides are often highly destructive.Reviewing and analyzing the causes,processes,impacts,and deficiencies in emergency response is critical for improving disaster prevention and management.From the night of July 21 to the morning of July 22,2024,the Kencho Shacha Gozdi Village in Gezei Gofa,Southern Nations,Nationalities,and Peoples'Region,Ethiopia,suffered heavy rainfall that triggered two landslides.By July25,this event had claimed at least 257 lives.This study presents a detailed characterization of the landslides using multi-source data.By analyzing the landslide disaster process,this study summarizes key lessons and provides suggestions for preventing rainfall-induced geological hazards.The results indicate that rainfall has the greatest impact on the occurrence of landslides,while lithology and human activities have promoted and strengthened the landslide disaster.Despite the active disaster response in the local area,many problems were still exposed in the emergency response work.This analysis offers valuable insights for mitigating rainfall-induced geological hazards and enhancing emergency response capabilities.展开更多
Purpose:The aim of this study was to summarize the evidence regarding whether pain reduction in individuals with chronic non-specific low back pain(CNSLBP)following conservative interventions is related to correspondi...Purpose:The aim of this study was to summarize the evidence regarding whether pain reduction in individuals with chronic non-specific low back pain(CNSLBP)following conservative interventions is related to corresponding improvements in balance control.Methods:Randomized controlled trials were identified from 5 databases(MEDLINE,Cochrane Library,Embase,Web of Science,and PsycINFO).Two reviewers independently screened and identified relevant studies that investigated the effects of non-surgical or non-pharmacological CNSLBP treatments on both pain intensity and balance control.Meta-regression analyses were performed to establish the associations between post-treatment changes in these 2 variables.Results:Thirty one studies involving 1280 participants with CNSLBP were included.Moderate-quality evidence suggested that pain reduction was associated with and explained 34%-45%of decreases in body sway,as measured by center-of-pressure(CoP)area and CoP velocity with eyes open.However,no significant association was observed between pain reduction and CoP area or velocity in anteroposterior/mediolateral directions.Similarly,there was no significant association between pain reduction and CoP distance or radius.Low-quality evidence indicated that pain relief explained a 15%improvement in one-leg stance with eyes open but not in the eyes-closed condition.Additionally,very low-quality evidence suggested that pain relief explained a 44%decrease in the static anteroposterior stability index with eyes closed but not in the eyes-open,mediolateral,or overall conditions.Furthermore,low-quality evidence indicated that reduced pain was associated with and accounted for 25%-43%of the improved composite and posteromedial scores of the star-excursion balance test,rather than the anterior and posterolateral scores.Conclusion:Depending on the type of balance assessment,pain relief following conservative interventions may slightly to moderately enhance balance control in individuals with CNSLBP.Clinicians should pay close attention to the balance control in patients with CNSLBP,particularly among older adults.展开更多
The formation of a pressure relief zone is crucial for rockbust prevention during drilling pressure relief.This study investi-gates the mechanical behavior of high-stress rock under real-time drilling conditions and e...The formation of a pressure relief zone is crucial for rockbust prevention during drilling pressure relief.This study investi-gates the mechanical behavior of high-stress rock under real-time drilling conditions and elucidates the mechanism behind the creation of the pressure relief zone.Utilizing the independently developed SG4500 drilling rig,we conducted a theoreti-cal analysis of the forces acting on the drill bit.The analysis showed that cutting depth is directly proportional to real-time drilling speed,while tangential and normal forces are influenced by drilling diameter.Uniaxial compression tests on red sandstone specimens under high-stress real-time drilling conditions examined the impacts of different drilling speeds(800,400,100 r/min)and diameters(6,8,10,12 mm)on rock mechanical behavior,rockburst characteristics,crack evolution,and peak elastic strain energy.The results indicate that decreasing drilling speed and increasing drilling diameter weaken rock mechanical behavior,including peak strength,Young's modulus,rockburst characteristics,and peak elastic strain energy.Crack evolution analysis reveals that smaller drilling diameters and higher drilling speeds promote the development of far-field cracks,while larger drilling diameters and lower drilling speeds lead to crack formation around the borehole,and significantly affecting rock failure mechanisms.Theoretical analysis further confirms the correlation between crack evolution and stress distribution surrounding the drilling.Under vertical stress,the cracks near the borehole formed during real-time drilling are mainly influenced by tangential compressive and tensile stresses.Overall,this study provides a new perspective on understanding the mechanisms of drilling pressure relief for rockburst prevention.展开更多
On the title photo you can see in the background the distinctive peak of the highest mountain of the Krkono?e Mountains,and the whole Czechia,Snězka 1603 m above sea level,which is unique not only in Central Europe w...On the title photo you can see in the background the distinctive peak of the highest mountain of the Krkono?e Mountains,and the whole Czechia,Snězka 1603 m above sea level,which is unique not only in Central Europe with its size,altitude,glacial and periglacial relief and arctic-alpine tundra.In the foreground of the photograph,an inconspicuous platform with several benches and concrete blocks can be seen.展开更多
In this work,the effect of ultrasonic vibration modes on the mechanical properties and relaxation of residual stress in 6061-T6 aluminum alloy was studied.A new ultrasonic vibration Johnson-Cook model was proposed,and...In this work,the effect of ultrasonic vibration modes on the mechanical properties and relaxation of residual stress in 6061-T6 aluminum alloy was studied.A new ultrasonic vibration Johnson-Cook model was proposed,and the relaxation and distribution of residual stress under ultrasonic vibration were predicted and analyzed using the finite element method(FEM).The mechanical properties of 6061-T6 aluminum alloy under different ultrasonic vibration modes were analyzed through experiments involving notched specimen tensile testing and scanning electron microscopy(SEM)analysis.The findings indicate that ultrasonic vibration treatment during deformation,unloading,and load-holding,as well as treatment with its natural ultrasonic frequency,can effectively release residual stress;however,treatment with its natural frequency has the highest rate of release up to 65.4%.Ultrasonic vibration treatment during deformation better inhibits fracture under the same conditions.The FEM results are in good agreement with the experimental results,and it can be used as a valid tool for predicting residual stress release under ultrasonic vibration.展开更多
Objective:Acute appendicitis,as a common clinical acute abdominal condition,has a significant impact on patient prognosis depending on the choice of treatment strategy.This study aims to systematically compare the cli...Objective:Acute appendicitis,as a common clinical acute abdominal condition,has a significant impact on patient prognosis depending on the choice of treatment strategy.This study aims to systematically compare the clinical efficacy and safety of surgical versus conservative treatment in patients with acute appendicitis.Methods:A total of 60 patients with acute appendicitis admitted to our hospital from August 2024 to July 2025 were selected as the study subjects and divided into a surgical group(n=30)and a conservative group(n=30)based on the treatment approach.The surgical group underwent abdominal incision appendectomy,while the conservative group received antibiotic therapy combined with symptomatic supportive treatment.Evaluation indicators included the treatment effective rate,symptom relief time,and complication incidence.Results:The treatment effective rate in the surgical group was 96.67%,significantly higher than that in the conservative group(76.67%)(p<0.05).In terms of symptom relief,the time to relief of abdominal pain(1.25±0.36 days)and fever(1.08±0.29 days)in the surgical group was significantly shorter than that in the conservative group(3.12±0.57 days and 2.89±0.61 days,respectively,p<0.001).The complication rates in the two groups were 10.00%and 13.33%,respectively(p>0.05).Conclusion:Surgical treatment for acute appendicitis demonstrates significant advantages in improving treatment efficacy and shortening the time to symptom relief,with a comparable risk of complications to conservative treatment.It is therefore worthy of clinical priority recommendation,particularly for patients without surgical contraindications.展开更多
Accurate acquisition of the rock stress is crucial for various rock engineering applications.The hollow inclusion (HI) technique is widely used for measuring in-situ rock stress.This technique calculates the stress te...Accurate acquisition of the rock stress is crucial for various rock engineering applications.The hollow inclusion (HI) technique is widely used for measuring in-situ rock stress.This technique calculates the stress tensor by measuring strain using an HI strain cell.However,existing analytical solutions for stress calculation based on an HI strain cell in a double-layer medium are not applicable when an HI strain cell is used in a three-layer medium,leading to erroneous stress calculations.To address this issue,this paper presents a method for calculating stress tensors in a three-layer medium using numerical simulations,specifically by obtaining a constitutive matrix that relates strain measurements to stress tensors in a three-layer medium.Furthermore,using Latin hypercube sampling (LHS) and orthogonal experimental design strategies,764 groups of numerical models encompassing various stress measurement scenarios have been established and calculated using FLAC^(3D)software.Finally,a surrogate model based on artificial neural network (ANN) was developed to predict constitutive matrices,achieving a goodness of fit (R^(2)) of 0.999 and a mean squared error (MSE) of 1.254.A software program has been developed from this surrogate model for ease of use in practical engineering applications.The method’s accuracy was verified through numerical simulations,analytical solution and laboratory experiment,demonstrating its effectiveness in calculating stress in a three-layer medium.The surrogate model was applied to calculate mining-induced stress in the roadway roof rock of a coal mine,a typical case for stress measurement in a three-layer medium.Errors in stress calculations arising from the use of existing analytical solutions were corrected.The study also highlights the significant errors associated with using double-layer analytical solutions in a three-layer medium,which could lead to inappropriate engineering design.展开更多
Experimental results from the Daniudi gas field enhance our understanding of mechanisms behind CO_(2) injection for enhanced recovery from tight-sand gas reservoirs.The results reveal that the diffusion coefficients o...Experimental results from the Daniudi gas field enhance our understanding of mechanisms behind CO_(2) injection for enhanced recovery from tight-sand gas reservoirs.The results reveal that the diffusion coefficients of CO_(2) in tight reservoirs range from 10-8m2/s to 10-9m2/s,correlating negatively with pore pressure and positively with pore radius.In these reservoirs,CO_(2) manifests a significantly higher adsorption capability compared to CH4,suggesting a competitive adsorption advantage.Further,the amount of adsorbed gas correlates negatively with core permeability and positively with pore pressure.In the late-stage depletion-drive development of tight-sand gas reservoirs,CO_(2) injection alleviates water locking and enhances gas-water flow,facilitating the recovery of trapped gas.The long-core CO_(2) flooding experiment results in a 14.11%increase in gas recovery efficiency.The effectiveness of CO_(2) -enhanced gas recovery (EGR) is primarily related to reservoir properties.Higher average permeability correlates with more effective CO_(2) -EGR.Although the rate and mode of injection have limited impacts on ultimate recovery efficiency,they influence CO_(2) breakthrough time.Specifically,a higher injection rate leads to earlier breakthrough,and the breakthrough under pulsed CO_(2) injection occurs later than that under continuous injection.展开更多
The 110-mining method,a rising and revolutionary non-pillar longwall mining method,can obviously expand coal extraction ratio and minimize roadway incidents.However,in case of composite hard roof,problems such as diff...The 110-mining method,a rising and revolutionary non-pillar longwall mining method,can obviously expand coal extraction ratio and minimize roadway incidents.However,in case of composite hard roof,problems such as difficulty in commanding the entry steadiness and insufficient fragmentation and bulking of the goaf gangue are prevalent.In this study,a 110-mining method for roadway surrounding rock stability control technology based on a compensation mechanism was proposed.First,the composite hard roof cutting short cantilever beam(SCB)model was built and the compensation mechanism including stress and space dual compensation was studied.Subsequently,the controllable elements influencing the roadway steadiness were confirmed to consequently put forward a control technology based on stress compensation for entry support and space compensation for the fragmentation and bulking of goaf gangue.The control technology was finally verified through onsite engineering experiments in terms of composite hard roof.The adoption of the 110-mining method with compensation control technology indicated good support effect on the roadway.The initial and residual expansion coefficients of the goaf gangue increased by 0.6 and 0.6,respectively,and the maximum and average working resistances of the working face support decreased by 10.9%and 13.8%,respectively.Consequently,the deformations of reserved entry decreased,and entry steadiness was enhanced.The presented technique and effects got probably have practical values for non-pillar mining functions in comparable field.展开更多
BACKGROUND Functional gastrointestinal disorders(FGIDs)are common gastrointestinal conditions that significantly impair patient quality of life.Current clinical treatment methods are relatively limited,making the sear...BACKGROUND Functional gastrointestinal disorders(FGIDs)are common gastrointestinal conditions that significantly impair patient quality of life.Current clinical treatment methods are relatively limited,making the search for more effective therapeutic strategies critically important.Latent myofascial trigger points(MTrPs)injection,as an emerging minimally invasive treatment method,has shown potential in alleviating muscle pain and improving function,but its application in FGIDs remains insufficiently validated.AIM To assess improvements in gastrointestinal symptom severity,quality of life indices,and treatment-related adverse events between the two therapeutic approaches.METHODS This single-blind randomized controlled study recruited 60 FGIDs patients from Qilu Hospital of Shandong University,randomly divided into an injection group(TI group)and an oral medication group(PO group)at a 1:1 ratio.The TI group received abdominal wall latent MTrPs injection therapy,while the PO group received oral symptomatic medication treatment.Primary outcome measures were gastrointestinal symptom severity scores(Gastrointestinal Symptom Rating Scale,Irritable Bowel Syndrome Severity Scoring System scales)at 2 weeks and 4 weeks after treatment completion.Secondary outcome measures included Gastrointestinal Quality of Life Index scores.Both groups underwent rigorous follow-up and assessment.RESULTS The TI group is anticipated to significantly outperform the PO group in gastrointestinal symptom relief and quality of life improvement.TI group patients are expected to show a notable decrease in symptom scores,increased quality of life index,and higher clinical effectiveness rate.Additionally,the TI group is projected to have a low adverse event rate and good safety profile.CONCLUSION Latent MTrPs injection therapy may represent an effective and safe new method for treating FGIDs.Compared to traditional oral medication treatment,this method demonstrates significant advantages in improving patient symptoms and quality of life.展开更多
During fully mechanized caving mining of thick coal seams,a large amount of strain energy accumulates in the roof,especially when the roof is thick and hard,making it difficultfor the roof to collapse naturally.When t...During fully mechanized caving mining of thick coal seams,a large amount of strain energy accumulates in the roof,especially when the roof is thick and hard,making it difficultfor the roof to collapse naturally.When the roof eventually collapses,the accumulated energy is released instantaneously,exerting a strong impact on the roadway.To address this issue,we proposed the synergistic control method of directional comprehensive pressure relief and energy-absorbing support(PREA)for roadways with hard roofs.In this study,we developed a three-dimensional physical model test apparatus for roof cutting and pressure relief.The 122108 ventilation roadway at the Caojiatan Coal Mine,which has a thick and hard roof,was taken as the engineering example.We analyzed the evolution patterns of stress and displacement in both the stope and the roadway surrounding rocks under different schemes.The PREA reinforcement mechanism for the roadway was investigated through comparative model tests between the new and original methods.The results showed that,compared to the original method,the new method reduced surrounding rock stress by up to 60.4%,and the roadway convergence decreased by up to 52.1%.Based on these results,we proposed corresponding engineering recommendations,which can guide fieldreinforcement design and application.The results demonstrate that the PREA method effectively reduces stress and ensures the safety and stability of the roadway.展开更多
文摘Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;"> century. The facts justifying the connection are given by Siberian Fan Reliefs and the Tunguska Cosmic Body. It is most natural to assume that we are dealing with the falling of numerous fragments of a collapsed comet. The more likely version is that the comet is captured by the Earth-Moon system and remains in Earth orbit for some time.
文摘Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20<sup>th</sup> century. These reliefs consist of several tens (up to hundreds) of stripes that have arisen as a result of the destruction of vegetation and the surface layer of the ground. Structures of stripes are extended, ranging in size from 6 km to ≥20 km, with a width of several kilometers. Every strip (scratch on the ground) is roughly estimated to be up to 50 m wide and ≥500 m long. The stripes start from one edge of the relief and stretch at inter-vals to the other, slightly diverging symmetrically from the central axis. It was determined that these reliefs are not associated with the movement of soil (avalanches, mudflows) or with the impact of air currents (hurricanes, storm, tornado). Geographically, these struc-tures of stripes are located within a circle with a radius of 770 km, described around the epicenter of the Tunguska catastrophe.
文摘Giant wooden reliefsillustrate some 45 ancientChinese myths, reflectingthe wisdom of the Chinesenation in antiquity. Eachboard depicts a legendaryscene, enabling viewers tovisualise the nature of theChinese nation and thespirit of the ancient country.
基金National Program of Foreign Experts of China(G2023026003L)National Natural Science Foundation of China(52475347)+4 种基金Postdoctoral Fund(2023M740475)International Science and Technology Cooperation Project of Henan Province(242102521057)Frontier Exploration Projects of Longmen Laboratory(LMQYTSKT016)Central Plains Science and Technology Innovation Leading TalentsProvincial Science and Technology R&D Program Joint Fund Projects(235200810030)。
文摘As service conditions become more challenging and production complexity increases,there is an increasing demand for enhanced comprehensive performance of ceramic/metal heterostructures.At present,brazing technique has been widely utilized for ceramic-metal heterogeneous joints.However,the residual stress relief in these welding joints is complicated and necessary.Because metals and ceramics have different properties,especially their coefficients of thermal expansion.Welding joints exhibit large residual stresses during the cooling process.The relatively high residual stresses may significantly degrade the joint properties.For this issue,four alleviation routes were reviewed:optimization of process parameters,setting an intermediate layer,surface structure modulation and particle-reinforced composite solder.The states and distribution patterns of residual stress in ceramic-metal brazed joints were summarized,and the generation and detection of residual stress were introduced.Eventually,upcoming prospects and challenges of residual stress research on ceramic/metal heterostructures were pointed out.
文摘After the earthquake struck Myanmar on March 28th,China NGO Network for International Exchanges(CNIE)immediately contacted the emergency management department for the registration process of non-governmental rescue forces participating in earthquake relief work and guided its member organisations and partners to orderly participate in the disaster relief.
基金supported by the National Institute of Natural Hazards,Ministry of Emergency Management of China(2023-JBKY-57)the National Natural Science Foundation of China(42077259)。
文摘Rainfall-induced landslides are often highly destructive.Reviewing and analyzing the causes,processes,impacts,and deficiencies in emergency response is critical for improving disaster prevention and management.From the night of July 21 to the morning of July 22,2024,the Kencho Shacha Gozdi Village in Gezei Gofa,Southern Nations,Nationalities,and Peoples'Region,Ethiopia,suffered heavy rainfall that triggered two landslides.By July25,this event had claimed at least 257 lives.This study presents a detailed characterization of the landslides using multi-source data.By analyzing the landslide disaster process,this study summarizes key lessons and provides suggestions for preventing rainfall-induced geological hazards.The results indicate that rainfall has the greatest impact on the occurrence of landslides,while lithology and human activities have promoted and strengthened the landslide disaster.Despite the active disaster response in the local area,many problems were still exposed in the emergency response work.This analysis offers valuable insights for mitigating rainfall-induced geological hazards and enhancing emergency response capabilities.
基金supported by GP Batteries Industrial Safety Trust Fund(Funding number:R-ZDDR).
文摘Purpose:The aim of this study was to summarize the evidence regarding whether pain reduction in individuals with chronic non-specific low back pain(CNSLBP)following conservative interventions is related to corresponding improvements in balance control.Methods:Randomized controlled trials were identified from 5 databases(MEDLINE,Cochrane Library,Embase,Web of Science,and PsycINFO).Two reviewers independently screened and identified relevant studies that investigated the effects of non-surgical or non-pharmacological CNSLBP treatments on both pain intensity and balance control.Meta-regression analyses were performed to establish the associations between post-treatment changes in these 2 variables.Results:Thirty one studies involving 1280 participants with CNSLBP were included.Moderate-quality evidence suggested that pain reduction was associated with and explained 34%-45%of decreases in body sway,as measured by center-of-pressure(CoP)area and CoP velocity with eyes open.However,no significant association was observed between pain reduction and CoP area or velocity in anteroposterior/mediolateral directions.Similarly,there was no significant association between pain reduction and CoP distance or radius.Low-quality evidence indicated that pain relief explained a 15%improvement in one-leg stance with eyes open but not in the eyes-closed condition.Additionally,very low-quality evidence suggested that pain relief explained a 44%decrease in the static anteroposterior stability index with eyes closed but not in the eyes-open,mediolateral,or overall conditions.Furthermore,low-quality evidence indicated that reduced pain was associated with and accounted for 25%-43%of the improved composite and posteromedial scores of the star-excursion balance test,rather than the anterior and posterolateral scores.Conclusion:Depending on the type of balance assessment,pain relief following conservative interventions may slightly to moderately enhance balance control in individuals with CNSLBP.Clinicians should pay close attention to the balance control in patients with CNSLBP,particularly among older adults.
基金supported by the National Natural Science Foundation of China(42077244)the Open Research Fund of Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization(2020-05)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX24_0434).
文摘The formation of a pressure relief zone is crucial for rockbust prevention during drilling pressure relief.This study investi-gates the mechanical behavior of high-stress rock under real-time drilling conditions and elucidates the mechanism behind the creation of the pressure relief zone.Utilizing the independently developed SG4500 drilling rig,we conducted a theoreti-cal analysis of the forces acting on the drill bit.The analysis showed that cutting depth is directly proportional to real-time drilling speed,while tangential and normal forces are influenced by drilling diameter.Uniaxial compression tests on red sandstone specimens under high-stress real-time drilling conditions examined the impacts of different drilling speeds(800,400,100 r/min)and diameters(6,8,10,12 mm)on rock mechanical behavior,rockburst characteristics,crack evolution,and peak elastic strain energy.The results indicate that decreasing drilling speed and increasing drilling diameter weaken rock mechanical behavior,including peak strength,Young's modulus,rockburst characteristics,and peak elastic strain energy.Crack evolution analysis reveals that smaller drilling diameters and higher drilling speeds promote the development of far-field cracks,while larger drilling diameters and lower drilling speeds lead to crack formation around the borehole,and significantly affecting rock failure mechanisms.Theoretical analysis further confirms the correlation between crack evolution and stress distribution surrounding the drilling.Under vertical stress,the cracks near the borehole formed during real-time drilling are mainly influenced by tangential compressive and tensile stresses.Overall,this study provides a new perspective on understanding the mechanisms of drilling pressure relief for rockburst prevention.
文摘On the title photo you can see in the background the distinctive peak of the highest mountain of the Krkono?e Mountains,and the whole Czechia,Snězka 1603 m above sea level,which is unique not only in Central Europe with its size,altitude,glacial and periglacial relief and arctic-alpine tundra.In the foreground of the photograph,an inconspicuous platform with several benches and concrete blocks can be seen.
基金Project(51775480)supported by the National Natural Science Foundation of ChinaProjects(E2018203143,E2022203050)supported by the Natural Science Foundation of Hebei Province,China。
文摘In this work,the effect of ultrasonic vibration modes on the mechanical properties and relaxation of residual stress in 6061-T6 aluminum alloy was studied.A new ultrasonic vibration Johnson-Cook model was proposed,and the relaxation and distribution of residual stress under ultrasonic vibration were predicted and analyzed using the finite element method(FEM).The mechanical properties of 6061-T6 aluminum alloy under different ultrasonic vibration modes were analyzed through experiments involving notched specimen tensile testing and scanning electron microscopy(SEM)analysis.The findings indicate that ultrasonic vibration treatment during deformation,unloading,and load-holding,as well as treatment with its natural ultrasonic frequency,can effectively release residual stress;however,treatment with its natural frequency has the highest rate of release up to 65.4%.Ultrasonic vibration treatment during deformation better inhibits fracture under the same conditions.The FEM results are in good agreement with the experimental results,and it can be used as a valid tool for predicting residual stress release under ultrasonic vibration.
文摘Objective:Acute appendicitis,as a common clinical acute abdominal condition,has a significant impact on patient prognosis depending on the choice of treatment strategy.This study aims to systematically compare the clinical efficacy and safety of surgical versus conservative treatment in patients with acute appendicitis.Methods:A total of 60 patients with acute appendicitis admitted to our hospital from August 2024 to July 2025 were selected as the study subjects and divided into a surgical group(n=30)and a conservative group(n=30)based on the treatment approach.The surgical group underwent abdominal incision appendectomy,while the conservative group received antibiotic therapy combined with symptomatic supportive treatment.Evaluation indicators included the treatment effective rate,symptom relief time,and complication incidence.Results:The treatment effective rate in the surgical group was 96.67%,significantly higher than that in the conservative group(76.67%)(p<0.05).In terms of symptom relief,the time to relief of abdominal pain(1.25±0.36 days)and fever(1.08±0.29 days)in the surgical group was significantly shorter than that in the conservative group(3.12±0.57 days and 2.89±0.61 days,respectively,p<0.001).The complication rates in the two groups were 10.00%and 13.33%,respectively(p>0.05).Conclusion:Surgical treatment for acute appendicitis demonstrates significant advantages in improving treatment efficacy and shortening the time to symptom relief,with a comparable risk of complications to conservative treatment.It is therefore worthy of clinical priority recommendation,particularly for patients without surgical contraindications.
基金funding support from the National Natural Science Foundation of China (Nos. 42477208 and 52079134)the Natural Science Foundation of Hubei Province, China (No. 2024AFA072)+2 种基金the Youth Innovation Promotion Association CAS (No. 2022332)the National Key R&D Program of China (No. 2024YFF0508203)the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety (Nos. SKLGME-JBGS2402 and SKLGME022022)。
文摘Accurate acquisition of the rock stress is crucial for various rock engineering applications.The hollow inclusion (HI) technique is widely used for measuring in-situ rock stress.This technique calculates the stress tensor by measuring strain using an HI strain cell.However,existing analytical solutions for stress calculation based on an HI strain cell in a double-layer medium are not applicable when an HI strain cell is used in a three-layer medium,leading to erroneous stress calculations.To address this issue,this paper presents a method for calculating stress tensors in a three-layer medium using numerical simulations,specifically by obtaining a constitutive matrix that relates strain measurements to stress tensors in a three-layer medium.Furthermore,using Latin hypercube sampling (LHS) and orthogonal experimental design strategies,764 groups of numerical models encompassing various stress measurement scenarios have been established and calculated using FLAC^(3D)software.Finally,a surrogate model based on artificial neural network (ANN) was developed to predict constitutive matrices,achieving a goodness of fit (R^(2)) of 0.999 and a mean squared error (MSE) of 1.254.A software program has been developed from this surrogate model for ease of use in practical engineering applications.The method’s accuracy was verified through numerical simulations,analytical solution and laboratory experiment,demonstrating its effectiveness in calculating stress in a three-layer medium.The surrogate model was applied to calculate mining-induced stress in the roadway roof rock of a coal mine,a typical case for stress measurement in a three-layer medium.Errors in stress calculations arising from the use of existing analytical solutions were corrected.The study also highlights the significant errors associated with using double-layer analytical solutions in a three-layer medium,which could lead to inappropriate engineering design.
基金funded by Basic Research Project of SINOPEC (P22202)。
文摘Experimental results from the Daniudi gas field enhance our understanding of mechanisms behind CO_(2) injection for enhanced recovery from tight-sand gas reservoirs.The results reveal that the diffusion coefficients of CO_(2) in tight reservoirs range from 10-8m2/s to 10-9m2/s,correlating negatively with pore pressure and positively with pore radius.In these reservoirs,CO_(2) manifests a significantly higher adsorption capability compared to CH4,suggesting a competitive adsorption advantage.Further,the amount of adsorbed gas correlates negatively with core permeability and positively with pore pressure.In the late-stage depletion-drive development of tight-sand gas reservoirs,CO_(2) injection alleviates water locking and enhances gas-water flow,facilitating the recovery of trapped gas.The long-core CO_(2) flooding experiment results in a 14.11%increase in gas recovery efficiency.The effectiveness of CO_(2) -enhanced gas recovery (EGR) is primarily related to reservoir properties.Higher average permeability correlates with more effective CO_(2) -EGR.Although the rate and mode of injection have limited impacts on ultimate recovery efficiency,they influence CO_(2) breakthrough time.Specifically,a higher injection rate leads to earlier breakthrough,and the breakthrough under pulsed CO_(2) injection occurs later than that under continuous injection.
基金This work described herein was supported by the Program of China Scholarship Council(202206430008)the National Natural Science Foundation of China(NSFC)(52074300 and 52304111)+1 种基金the Yueqi Young Scholars Project of China University of Mining and Technology Beijing(2602021RC84)the Guizhou province science and technology planning project([2020]3007 and[2020]2Y019).
文摘The 110-mining method,a rising and revolutionary non-pillar longwall mining method,can obviously expand coal extraction ratio and minimize roadway incidents.However,in case of composite hard roof,problems such as difficulty in commanding the entry steadiness and insufficient fragmentation and bulking of the goaf gangue are prevalent.In this study,a 110-mining method for roadway surrounding rock stability control technology based on a compensation mechanism was proposed.First,the composite hard roof cutting short cantilever beam(SCB)model was built and the compensation mechanism including stress and space dual compensation was studied.Subsequently,the controllable elements influencing the roadway steadiness were confirmed to consequently put forward a control technology based on stress compensation for entry support and space compensation for the fragmentation and bulking of goaf gangue.The control technology was finally verified through onsite engineering experiments in terms of composite hard roof.The adoption of the 110-mining method with compensation control technology indicated good support effect on the roadway.The initial and residual expansion coefficients of the goaf gangue increased by 0.6 and 0.6,respectively,and the maximum and average working resistances of the working face support decreased by 10.9%and 13.8%,respectively.Consequently,the deformations of reserved entry decreased,and entry steadiness was enhanced.The presented technique and effects got probably have practical values for non-pillar mining functions in comparable field.
文摘BACKGROUND Functional gastrointestinal disorders(FGIDs)are common gastrointestinal conditions that significantly impair patient quality of life.Current clinical treatment methods are relatively limited,making the search for more effective therapeutic strategies critically important.Latent myofascial trigger points(MTrPs)injection,as an emerging minimally invasive treatment method,has shown potential in alleviating muscle pain and improving function,but its application in FGIDs remains insufficiently validated.AIM To assess improvements in gastrointestinal symptom severity,quality of life indices,and treatment-related adverse events between the two therapeutic approaches.METHODS This single-blind randomized controlled study recruited 60 FGIDs patients from Qilu Hospital of Shandong University,randomly divided into an injection group(TI group)and an oral medication group(PO group)at a 1:1 ratio.The TI group received abdominal wall latent MTrPs injection therapy,while the PO group received oral symptomatic medication treatment.Primary outcome measures were gastrointestinal symptom severity scores(Gastrointestinal Symptom Rating Scale,Irritable Bowel Syndrome Severity Scoring System scales)at 2 weeks and 4 weeks after treatment completion.Secondary outcome measures included Gastrointestinal Quality of Life Index scores.Both groups underwent rigorous follow-up and assessment.RESULTS The TI group is anticipated to significantly outperform the PO group in gastrointestinal symptom relief and quality of life improvement.TI group patients are expected to show a notable decrease in symptom scores,increased quality of life index,and higher clinical effectiveness rate.Additionally,the TI group is projected to have a low adverse event rate and good safety profile.CONCLUSION Latent MTrPs injection therapy may represent an effective and safe new method for treating FGIDs.Compared to traditional oral medication treatment,this method demonstrates significant advantages in improving patient symptoms and quality of life.
基金supported by the National Natural Science Foundation of China(Grant Nos.U24A2088 and 42277174)the Fundamental Research Funds for the Central Universities,China(Grant No.2024JCCXSB01).
文摘During fully mechanized caving mining of thick coal seams,a large amount of strain energy accumulates in the roof,especially when the roof is thick and hard,making it difficultfor the roof to collapse naturally.When the roof eventually collapses,the accumulated energy is released instantaneously,exerting a strong impact on the roadway.To address this issue,we proposed the synergistic control method of directional comprehensive pressure relief and energy-absorbing support(PREA)for roadways with hard roofs.In this study,we developed a three-dimensional physical model test apparatus for roof cutting and pressure relief.The 122108 ventilation roadway at the Caojiatan Coal Mine,which has a thick and hard roof,was taken as the engineering example.We analyzed the evolution patterns of stress and displacement in both the stope and the roadway surrounding rocks under different schemes.The PREA reinforcement mechanism for the roadway was investigated through comparative model tests between the new and original methods.The results showed that,compared to the original method,the new method reduced surrounding rock stress by up to 60.4%,and the roadway convergence decreased by up to 52.1%.Based on these results,we proposed corresponding engineering recommendations,which can guide fieldreinforcement design and application.The results demonstrate that the PREA method effectively reduces stress and ensures the safety and stability of the roadway.
