A novel temperature-preserved core chamber designed for depths exceeding 5000 m has been developed to enhance the scientific understanding of deep oil and gas reservoirs.This temperature-preserved core chamber employs...A novel temperature-preserved core chamber designed for depths exceeding 5000 m has been developed to enhance the scientific understanding of deep oil and gas reservoirs.This temperature-preserved core chamber employs an innovative vacuum layer for temperature preservation and is compatible with a temperature-pressure preserved coring system.The design principles and key parameters of the temperature-preserved core chamber were determined through static analysis.Numerical simulations assessed the mechanical properties of 70,85,and 100 MPa core chambers under conditions of 120-150℃.The results demonstrate that the temperature-preserved core chambers withstand the applied stresses without plastic deformation,and the vacuum layer maintains its integrity under these conditions.A 70 MPa class core chamber prototype was manufactured,and system integration tests were performed on a self-developed in-situ coring platform.The system demonstrated stable operation at 70 MPa for 120 min,with pressure fluctuations within 5%.Additionally,the integrated system operated without interference,enabling the successful extraction of cores with a 50 mm diameter.These findings provide valuable theoretical guidance and design recommendations for advancing oil and gas in-situ temperature-pressure preserved coring technologies in high-temperature and high-pressure environments.展开更多
The Martian core mainly contains iron,nickel and some light elements.However,controversies remain about the structure and chemical composition of the Martian core due to a lack of samples and marsquake data.Recently,t...The Martian core mainly contains iron,nickel and some light elements.However,controversies remain about the structure and chemical composition of the Martian core due to a lack of samples and marsquake data.Recently,the InSight lander collected long-term marsquake data,which improved the Martian interior structure model.B ased on the preliminary analysis of marsquake data,Mars has a molten liquid core with a radius of around 1700 km.As the Martian core has a smaller density and lower temperature than pure iron at corresponding pressure and temperature conditions,some light elements are introduced to reduce the density and liquidus temperature.With various methods for seismic analysis,in-situ high-pressure and high-temperature experiments,and first-principal calculations,the Martian core composition and evolution models have been updated in the past few years.Here,we review those studies on the light elements in the Martian core from four aspects including(1)high-temperature and high-pressure experiments,(2)marsquake data,(3)mineral physics model with molecular dynamics simulations and(4)cosmochemistry investigation.We discussed the effect of different light elements on the Martian core s density,sound velocity and liquidus temperature.Moreover,the review examines the varieties,abundances and forms of light elements in the Martian core.展开更多
Low reactivity and appropriate wettability between molten superalloys and ceramic materials are crucial for the production of high-quality superalloy castings.The sessile-drop experiment was employed to systematically...Low reactivity and appropriate wettability between molten superalloys and ceramic materials are crucial for the production of high-quality superalloy castings.The sessile-drop experiment was employed to systematically investigate the interfacial reaction and wettability between the 4777DS1 superalloy and SiO_(2)-based ceramic core at various temperatures(1,480℃,1,500℃,1,520℃,and 1,550℃).The wetting behavior and interfacial reaction products at different temperatures were analyzed by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and X-ray diffraction(XRD).The interfacial reaction process and products were discussed,and the thermodynamic behavior and interfacial reaction mechanisms were elucidated.The results demonstrate that the wetting behavior and interfacial reaction between the 4777DS1 alloy and the ceramic core are significantly influenced by temperature.The wettability angle exhibits a trend of initial decrease followed by an increase with rising temperature,reaching a maximum of 139°at 1,480℃,indicating poorer wettability of the 4777DS1 superalloy with the ceramic core and better casting properties at this specific temperature.The most intense interfacial reaction occurs at 1,520℃,resulting in the formation of the main interfacial reaction products such as Al_(2)O_(3),SiO_(2),and HfO_(2).Additionally,some crystal-like products rich in Si and Hf distribute on the reaction layer.展开更多
[Objectives]To investigate the clinical efficacy of core stability training combined with conventional rehabilitation in the functional recovery of patients suffering from chronic low back pain.[Methods]A randomized c...[Objectives]To investigate the clinical efficacy of core stability training combined with conventional rehabilitation in the functional recovery of patients suffering from chronic low back pain.[Methods]A randomized controlled trial design was employed in this study.Ninety patients with chronic low back pain were recruited and randomly assigned to either a control group(n=45),which received conventional rehabilitation,or an experimental group(n=45),which received conventional rehabilitation combined with core stability training.Both groups underwent treatment for 6 weeks.Assessments were conducted using the visual analogue scale(VAS),Oswestry disability index(ODI),and finger-to-floor test prior to treatment,6 weeks following treatment,and during the follow-up period,respectively.[Results]Prior to treatment,no statistically significant differences were observed between the two patient groups in terms of general information and various baseline measurements(P>0.05).Following 6 weeks of treatment and throughout the follow-up period,both groups demonstrated significant improvements in VAS scores,ODI scores,and lumbar anteflexion range of motion compared to baseline measurements(P<0.05).Notably,the magnitude of improvement in the experimental group exceeded that of the control group,with this inter-group difference reaching statistical significance(P<0.05).No serious adverse reactions were reported during the treatment process.[Conclusions]Core stability training combined with conventional rehabilitation can significantly enhance the alleviation of pain and functional impairments in patients suffering from chronic low back pain.This approach holds valuable implications for the optimization of rehabilitation treatment protocols.展开更多
We read with great interest Deng et al.’s study 1 comparing sextant(6-core)and 12-core systematic biopsy in theMRI-targeted era,which valuably challenges the“more cores=higher accuracy”dogma by proposing a precisio...We read with great interest Deng et al.’s study 1 comparing sextant(6-core)and 12-core systematic biopsy in theMRI-targeted era,which valuably challenges the“more cores=higher accuracy”dogma by proposing a precision sampling strategy based on prostate cancer’s spatial distribution,aligning with personalized diagnosis trends.展开更多
Within contemporary healthcare systems, professional identity among specialized nurses serves as a pivotal intrinsic factor influencing the development of their core competencies. This review synthesizes existing rese...Within contemporary healthcare systems, professional identity among specialized nurses serves as a pivotal intrinsic factor influencing the development of their core competencies. This review synthesizes existing research, revealing that professional identity positively impacts the development of core competencies through multiple pathways, including psychological drive, behavioral facilitation, teamwork, and career stability. Building on this analysis, this paper proposes systematic enhancement strategies from four dimensions: education and training, organizational environment, cultural development, and individual growth, aiming to provide a reference for nursing practice and professional development.展开更多
Rational design of non-noble electrocatalysts with high performance for oxygen evolution reaction(OER)still remains a challenge.In this study,a ZIF-derived electrocatalyst(Co@Fe-P)with a core-shell structure is design...Rational design of non-noble electrocatalysts with high performance for oxygen evolution reaction(OER)still remains a challenge.In this study,a ZIF-derived electrocatalyst(Co@Fe-P)with a core-shell structure is designed by using Co-compounds as the core and PO_(4)^(3-)decorated Fe-compounds as the shell.The inner Co-core and outer Fe-shell are connected through Co-O-Fe and Fe-O-P linkage.The Co@Fe-P electrocatalyst exhibits an enhanced performance for OER with a low overpotential(280 mV),low Tafel slope(41.9 mV dec^(-1))at 10 mA cm^(-2),and a 60-h durability.The electron transfer from the CoOOH-core to the FeOOH-shell is greatly facilitated,which improves the OER activity of Co@Fe-P kinetically.Theoretical calculations indicate that the interaction of Co-O-Fe and Fe-O-P in Co@Fe-P reduces the overlap between the O 2p and Fe 3d orbitals,which greatly facilitates the transformation from*OH to*O during the OER process via the adsorbate evolution mechanism(AEM)pathway.This finding provides insight for the design of efficient electrocatalysts for OER.展开更多
Liquid core reduction(LCR)technology,originally developed for continuous thin-slab casting,allows space for a submerged entry nozzle in a mold while improving production efficiency.Recent experimental attempts explore...Liquid core reduction(LCR)technology,originally developed for continuous thin-slab casting,allows space for a submerged entry nozzle in a mold while improving production efficiency.Recent experimental attempts explore the implementation of LCR in regular slab casting processes.However,regular slabs(2–3 times thicker than thin slabs)face critical challenges in terms of excessive deformation and stress concentration under external forces,which induce intermediate cracks and thus hinder successful LCR adoption in regular slab production.This study evaluates the feasibility of LCR for producing regular slabs and identifies optimal reduction parameters to prevent crack initiation.A three-dimensional thermal–mechanical coupled model is proposed using the finite element method(FEM),integrated with the equivalent replacement liquid steel(ERLS)method and the normalized Cockcroft–Latham damage model,to achieve quantitative prediction of intermediate crack risk during the LCR process.The ERLS model simulates the extrusion flow and expulsion behavior of the liquid core,and its accuracy is validated against actual production measurements.To identify the critical damage value leading to intermediate crack initiation,this study conducts a consistency analysis between high-temperature tensile tests and FEM-based simulations using damage models.Based on this value,crack prediction is performed for Q355 slabs with cross-sectional dimensions of 170 mm×1450 mm.Using the prediction results,an optimal reduction scheme is determined,wherein the second segment accounts for 50%of the total reduction,the third segment for 32.5%,and the fourth segment for 17.5%,with the theoretical value of maximum reduction being 34 mm.These results provide actionable guidelines for the potential implementation of LCR in regular slab-casting systems.展开更多
目的探究乳腺癌保乳术后美学效果客观评价工具BCCT.core(breast cancer conservative treatment.cosmetic results,BCCT.core)与日本乳腺癌学会(Japanese breast cancer society,JBCS)主观评价量表评分之间的一致性,为BCCT.core在临床...目的探究乳腺癌保乳术后美学效果客观评价工具BCCT.core(breast cancer conservative treatment.cosmetic results,BCCT.core)与日本乳腺癌学会(Japanese breast cancer society,JBCS)主观评价量表评分之间的一致性,为BCCT.core在临床应用提供可靠的循证依据。方法自2021年1月至2024年12月,甘肃中医药大学第三附属医院纳入107例接受乳腺癌保乳术的患者,其中传统保乳手术46例(43%)、整形保乳手术34例(32%)、腔镜保乳手术27例(25%)。通过BCCT.core软件对患者术后胸部正面照片进行自动化美学分析,同时3名乳腺外科医师使用JBCS量表进行评分。采用组内相关系数(ICC)评估医师间评分的一致性;Spearman等级相关系数对BCCT.core软件评分与医师评分进行相关性分析。结果医师间评分呈现中等一致性(ICC相关系数为0.63);BCCT.core软件评分与3名医师评分均值表现出高度相关性(Spearman's rho=0.87,P<0.001)。与医师使用JBCS量表评价相比,BCCT.core软件操作简便,高效,评价标准化以及结果可重复等优势。因此,在临床应用中,BCCT.core软件能够节省时间及人力物力成本。结论BCCT.core软件的评价结果与医师主观评分具有高度相关性和可比性,其客观性及可靠性使其可作为乳腺癌保乳术后美学效果评价的辅助工具。展开更多
Natural gas hydrate(NGH)holds great promise as a source of clean energy.It is critical for acquiring the largest possible in situ NGH core for NGH eigen features and resource assessment.However,the existing NGH coring...Natural gas hydrate(NGH)holds great promise as a source of clean energy.It is critical for acquiring the largest possible in situ NGH core for NGH eigen features and resource assessment.However,the existing NGH coring technology has limitations,such as temperature increments,limited coring diameters,low coring rates,and complex coring structures.Therefore,this study designs and proposes an NGH freezing coring(NGHFC)method and verifies the freezing and coring capacities of the NGHFC method in laboratories and experimental wells.Results suggest that NGHFC shows good freezing and heat-retention properties.A freezing core heat transfer model is developed.According to the actual air temperature and operating time,the optimum initial temperature of the cold source can be determined using this model.The average coring rate of NGHFC can reach 77.86%.The research results will provide a new idea of coring gas hydrates.展开更多
With the increasing depth of coal mining,the requirements for coring devices that maintain pressure are increasing.To adapt to the special environment in deep coal seams and improve the accuracy of testing gas content...With the increasing depth of coal mining,the requirements for coring devices that maintain pressure are increasing.To adapt to the special environment in deep coal seams and improve the accuracy of testing gas content,a low-disturbance pressure-preserving corer was developed.The measurement of gas content using this corer was analyzed.The coring test platform was used to complete a coring function test.A pressurized core with a diameter of 50 mm was obtained.The pressure was 0.15 MPa,which was equal to the pressure of the liquid column of the cored layer,indicating that the corer can be successfully used in a mud environment.Next,a pressure test of the corer was conducted.The results showed that under conditions of low pressure(8 MPa)and high pressure(25 MPa),the internal pressure of the corer remained stable for more than 1 h,indicating that the corer has good ability to maintain pressure.Therefore,the corer can be applied at deep coal mine sites.The results of this research can be used to promote the safe exploitation of deep coal mines and the exploitation of methane resources in coalbeds.展开更多
The paper presents the design and preliminary test results of a corer used for hard seafloor sediments sampling. Generally the sediment cores are provided by either gravity-type coting or deep-ocean drilling for a ran...The paper presents the design and preliminary test results of a corer used for hard seafloor sediments sampling. Generally the sediment cores are provided by either gravity-type coting or deep-ocean drilling for a range of studies. However, in consideration of the operability and available sample length in collecting hard sediments, these methods exhibit no advantages. In this paper, a new corer which can exploit both hydrostatic energy and gravity energy for hard sediments coting is presented. The hydrostatic energy is provided by pressure differential between ambient seawater pressure and air pressure in an empty cavity. During sampling process, the corer penetrates into the sediment like a gravity corer and then automatically shifts to the percussion mode. The experiments in the laboratory indicate that the corer can complete 40 cycles in the sea with a cycle time of 2.8 seconds in percussion mode and impact the sample tube with the velocity of 0.2 m/s during each cycle. Besides, its adjustable falling velocity can make the corer achieve the maximum efficiency in coring different sediments.展开更多
Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression an...Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression and permeability tests to investigate the mechanical and seepage properties of tight sandstone.A digital core of tight sandstone was built using Computed Tomography(CT)scanning,which was divided into matrix and pore phases by a pore equivalent diameter threshold.A fluid-solid coupling model was established to investigate the seepage characteristics at micro-scale.The results showed that increasing the confining pressure decreased porosity,permeability,and flow velocity,with the pore phase becoming the dominant seepage channel.Cracks and large pores closed first under increasing pressure,resulted in a steep drop in permeability.However,permeability slightly decreased under high confining pressure,which followed a first-order exponential function.Flow velocity increased with seepage pressure.And the damage mainly occurred in stress-concentration regions under low seepage pressure.Seepage behavior followed linear Darcy flow,the damage emerged at seepage entrances under high pressure,which decreased rock elastic modulus and significantly increased permeability.展开更多
Gas content serves as a critical indicator for assessing the resource potential of deep coal mines and forecasting coal mine gas outburst risks.However,existing sampling technologies face challenges in maintaining the...Gas content serves as a critical indicator for assessing the resource potential of deep coal mines and forecasting coal mine gas outburst risks.However,existing sampling technologies face challenges in maintaining the integrity of gas content within samples and are often constrained by estimation errors inherent in empirical formulas,which results in inaccurate gas content measurements.This study introduces a lightweight,in-situ pressure-and gas-preserved corer designed to collect coal samples under the pressure conditions at the sampling point,effectively preventing gas loss during transfer and significantly improving measurement accuracy.Additionally,a gas migration model for deep coal mines was developed to elucidate gas migration characteristics under pressure-preserved coring conditions.The model offers valuable insights for optimizing coring parameters,demonstrating that both minimizing the coring hole diameter and reducing the pressure difference between the coring-point pressure and the original pore pressure can effectively improve the precision of gas content measurements.Coring tests conducted at an experimental base validated the performance of the corer and its effectiveness in sample collection.Furthermore,successful horizontal coring tests conducted in an underground coal mine roadway demonstrated that the measured gas content using pressure-preserved coring was 34%higher than that obtained through open sampling methods.展开更多
基金the financial support from the National Key R&D Program of China(No.2022YFB3706604)the National Natural Science Foundation of China(52304033)+2 种基金the National Natural Science Foundation of China(No.51827901)Sichuan Science and Technology Program(2023NSFSC0790)China Postdoctoral Science Foundation(No.2023M742446)。
文摘A novel temperature-preserved core chamber designed for depths exceeding 5000 m has been developed to enhance the scientific understanding of deep oil and gas reservoirs.This temperature-preserved core chamber employs an innovative vacuum layer for temperature preservation and is compatible with a temperature-pressure preserved coring system.The design principles and key parameters of the temperature-preserved core chamber were determined through static analysis.Numerical simulations assessed the mechanical properties of 70,85,and 100 MPa core chambers under conditions of 120-150℃.The results demonstrate that the temperature-preserved core chambers withstand the applied stresses without plastic deformation,and the vacuum layer maintains its integrity under these conditions.A 70 MPa class core chamber prototype was manufactured,and system integration tests were performed on a self-developed in-situ coring platform.The system demonstrated stable operation at 70 MPa for 120 min,with pressure fluctuations within 5%.Additionally,the integrated system operated without interference,enabling the successful extraction of cores with a 50 mm diameter.These findings provide valuable theoretical guidance and design recommendations for advancing oil and gas in-situ temperature-pressure preserved coring technologies in high-temperature and high-pressure environments.
基金financially supported by the National Natural Science Foundation of China(grant no.42120104005)Guizhou Provincial 2021 Science and Technology Subsidies(grant no.GZ2021SIG)+1 种基金Guizhou Provincial Science and Technology Projects(grant nos.ZK[2024]087GCC[2023]060)。
文摘The Martian core mainly contains iron,nickel and some light elements.However,controversies remain about the structure and chemical composition of the Martian core due to a lack of samples and marsquake data.Recently,the InSight lander collected long-term marsquake data,which improved the Martian interior structure model.B ased on the preliminary analysis of marsquake data,Mars has a molten liquid core with a radius of around 1700 km.As the Martian core has a smaller density and lower temperature than pure iron at corresponding pressure and temperature conditions,some light elements are introduced to reduce the density and liquidus temperature.With various methods for seismic analysis,in-situ high-pressure and high-temperature experiments,and first-principal calculations,the Martian core composition and evolution models have been updated in the past few years.Here,we review those studies on the light elements in the Martian core from four aspects including(1)high-temperature and high-pressure experiments,(2)marsquake data,(3)mineral physics model with molecular dynamics simulations and(4)cosmochemistry investigation.We discussed the effect of different light elements on the Martian core s density,sound velocity and liquidus temperature.Moreover,the review examines the varieties,abundances and forms of light elements in the Martian core.
基金supported by the fund of State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment(No.DEC8300CG202210353EE280297)the China Postdoctoral Science Foundation(No.2021M692555)+1 种基金the Shaanxi Province Qinchuangyuan‘Scientists+Engineers’Team Building Project(No.2023KXJ-266)the Fundamental Research Funds for the Central Universities(No.xzy012023145)。
文摘Low reactivity and appropriate wettability between molten superalloys and ceramic materials are crucial for the production of high-quality superalloy castings.The sessile-drop experiment was employed to systematically investigate the interfacial reaction and wettability between the 4777DS1 superalloy and SiO_(2)-based ceramic core at various temperatures(1,480℃,1,500℃,1,520℃,and 1,550℃).The wetting behavior and interfacial reaction products at different temperatures were analyzed by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and X-ray diffraction(XRD).The interfacial reaction process and products were discussed,and the thermodynamic behavior and interfacial reaction mechanisms were elucidated.The results demonstrate that the wetting behavior and interfacial reaction between the 4777DS1 alloy and the ceramic core are significantly influenced by temperature.The wettability angle exhibits a trend of initial decrease followed by an increase with rising temperature,reaching a maximum of 139°at 1,480℃,indicating poorer wettability of the 4777DS1 superalloy with the ceramic core and better casting properties at this specific temperature.The most intense interfacial reaction occurs at 1,520℃,resulting in the formation of the main interfacial reaction products such as Al_(2)O_(3),SiO_(2),and HfO_(2).Additionally,some crystal-like products rich in Si and Hf distribute on the reaction layer.
文摘[Objectives]To investigate the clinical efficacy of core stability training combined with conventional rehabilitation in the functional recovery of patients suffering from chronic low back pain.[Methods]A randomized controlled trial design was employed in this study.Ninety patients with chronic low back pain were recruited and randomly assigned to either a control group(n=45),which received conventional rehabilitation,or an experimental group(n=45),which received conventional rehabilitation combined with core stability training.Both groups underwent treatment for 6 weeks.Assessments were conducted using the visual analogue scale(VAS),Oswestry disability index(ODI),and finger-to-floor test prior to treatment,6 weeks following treatment,and during the follow-up period,respectively.[Results]Prior to treatment,no statistically significant differences were observed between the two patient groups in terms of general information and various baseline measurements(P>0.05).Following 6 weeks of treatment and throughout the follow-up period,both groups demonstrated significant improvements in VAS scores,ODI scores,and lumbar anteflexion range of motion compared to baseline measurements(P<0.05).Notably,the magnitude of improvement in the experimental group exceeded that of the control group,with this inter-group difference reaching statistical significance(P<0.05).No serious adverse reactions were reported during the treatment process.[Conclusions]Core stability training combined with conventional rehabilitation can significantly enhance the alleviation of pain and functional impairments in patients suffering from chronic low back pain.This approach holds valuable implications for the optimization of rehabilitation treatment protocols.
文摘We read with great interest Deng et al.’s study 1 comparing sextant(6-core)and 12-core systematic biopsy in theMRI-targeted era,which valuably challenges the“more cores=higher accuracy”dogma by proposing a precision sampling strategy based on prostate cancer’s spatial distribution,aligning with personalized diagnosis trends.
文摘Within contemporary healthcare systems, professional identity among specialized nurses serves as a pivotal intrinsic factor influencing the development of their core competencies. This review synthesizes existing research, revealing that professional identity positively impacts the development of core competencies through multiple pathways, including psychological drive, behavioral facilitation, teamwork, and career stability. Building on this analysis, this paper proposes systematic enhancement strategies from four dimensions: education and training, organizational environment, cultural development, and individual growth, aiming to provide a reference for nursing practice and professional development.
基金financially supported by the National Natural Science Foundation of China(Nos.22372143 and 22208281)the Hebei Natural Science Foundation(Nos.B2023203001 and B2025203050)the Science Research Project of Hebei Education Department(BJK2024122)。
文摘Rational design of non-noble electrocatalysts with high performance for oxygen evolution reaction(OER)still remains a challenge.In this study,a ZIF-derived electrocatalyst(Co@Fe-P)with a core-shell structure is designed by using Co-compounds as the core and PO_(4)^(3-)decorated Fe-compounds as the shell.The inner Co-core and outer Fe-shell are connected through Co-O-Fe and Fe-O-P linkage.The Co@Fe-P electrocatalyst exhibits an enhanced performance for OER with a low overpotential(280 mV),low Tafel slope(41.9 mV dec^(-1))at 10 mA cm^(-2),and a 60-h durability.The electron transfer from the CoOOH-core to the FeOOH-shell is greatly facilitated,which improves the OER activity of Co@Fe-P kinetically.Theoretical calculations indicate that the interaction of Co-O-Fe and Fe-O-P in Co@Fe-P reduces the overlap between the O 2p and Fe 3d orbitals,which greatly facilitates the transformation from*OH to*O during the OER process via the adsorbate evolution mechanism(AEM)pathway.This finding provides insight for the design of efficient electrocatalysts for OER.
基金financially supported by the Na-tional Natural Science Foundation of China (No.52474355)the Fundamental Research Funds for the Central Uni-versities,China (No.N25DCG006).
文摘Liquid core reduction(LCR)technology,originally developed for continuous thin-slab casting,allows space for a submerged entry nozzle in a mold while improving production efficiency.Recent experimental attempts explore the implementation of LCR in regular slab casting processes.However,regular slabs(2–3 times thicker than thin slabs)face critical challenges in terms of excessive deformation and stress concentration under external forces,which induce intermediate cracks and thus hinder successful LCR adoption in regular slab production.This study evaluates the feasibility of LCR for producing regular slabs and identifies optimal reduction parameters to prevent crack initiation.A three-dimensional thermal–mechanical coupled model is proposed using the finite element method(FEM),integrated with the equivalent replacement liquid steel(ERLS)method and the normalized Cockcroft–Latham damage model,to achieve quantitative prediction of intermediate crack risk during the LCR process.The ERLS model simulates the extrusion flow and expulsion behavior of the liquid core,and its accuracy is validated against actual production measurements.To identify the critical damage value leading to intermediate crack initiation,this study conducts a consistency analysis between high-temperature tensile tests and FEM-based simulations using damage models.Based on this value,crack prediction is performed for Q355 slabs with cross-sectional dimensions of 170 mm×1450 mm.Using the prediction results,an optimal reduction scheme is determined,wherein the second segment accounts for 50%of the total reduction,the third segment for 32.5%,and the fourth segment for 17.5%,with the theoretical value of maximum reduction being 34 mm.These results provide actionable guidelines for the potential implementation of LCR in regular slab-casting systems.
文摘目的探究乳腺癌保乳术后美学效果客观评价工具BCCT.core(breast cancer conservative treatment.cosmetic results,BCCT.core)与日本乳腺癌学会(Japanese breast cancer society,JBCS)主观评价量表评分之间的一致性,为BCCT.core在临床应用提供可靠的循证依据。方法自2021年1月至2024年12月,甘肃中医药大学第三附属医院纳入107例接受乳腺癌保乳术的患者,其中传统保乳手术46例(43%)、整形保乳手术34例(32%)、腔镜保乳手术27例(25%)。通过BCCT.core软件对患者术后胸部正面照片进行自动化美学分析,同时3名乳腺外科医师使用JBCS量表进行评分。采用组内相关系数(ICC)评估医师间评分的一致性;Spearman等级相关系数对BCCT.core软件评分与医师评分进行相关性分析。结果医师间评分呈现中等一致性(ICC相关系数为0.63);BCCT.core软件评分与3名医师评分均值表现出高度相关性(Spearman's rho=0.87,P<0.001)。与医师使用JBCS量表评价相比,BCCT.core软件操作简便,高效,评价标准化以及结果可重复等优势。因此,在临床应用中,BCCT.core软件能够节省时间及人力物力成本。结论BCCT.core软件的评价结果与医师主观评分具有高度相关性和可比性,其客观性及可靠性使其可作为乳腺癌保乳术后美学效果评价的辅助工具。
基金supported by the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2019ZT08G315)National Natural Science Foundation of China No.51827901 and U2013603Shenzhen Basic Research Project(JCYJ20190808153416970)
文摘Natural gas hydrate(NGH)holds great promise as a source of clean energy.It is critical for acquiring the largest possible in situ NGH core for NGH eigen features and resource assessment.However,the existing NGH coring technology has limitations,such as temperature increments,limited coring diameters,low coring rates,and complex coring structures.Therefore,this study designs and proposes an NGH freezing coring(NGHFC)method and verifies the freezing and coring capacities of the NGHFC method in laboratories and experimental wells.Results suggest that NGHFC shows good freezing and heat-retention properties.A freezing core heat transfer model is developed.According to the actual air temperature and operating time,the optimum initial temperature of the cold source can be determined using this model.The average coring rate of NGHFC can reach 77.86%.The research results will provide a new idea of coring gas hydrates.
基金supported by the National Natural Science Foundation of China(No.51827901)the National Natural Science Foundation of China(No.52225403)+1 种基金the Program for Guangdong Introducing Innovative and Entrepreneurial Teams of China(No.2019ZT08G315)the Sichuan Science and Technology Program of China(No.2023NSFSC0780).
文摘With the increasing depth of coal mining,the requirements for coring devices that maintain pressure are increasing.To adapt to the special environment in deep coal seams and improve the accuracy of testing gas content,a low-disturbance pressure-preserving corer was developed.The measurement of gas content using this corer was analyzed.The coring test platform was used to complete a coring function test.A pressurized core with a diameter of 50 mm was obtained.The pressure was 0.15 MPa,which was equal to the pressure of the liquid column of the cored layer,indicating that the corer can be successfully used in a mud environment.Next,a pressure test of the corer was conducted.The results showed that under conditions of low pressure(8 MPa)and high pressure(25 MPa),the internal pressure of the corer remained stable for more than 1 h,indicating that the corer has good ability to maintain pressure.Therefore,the corer can be applied at deep coal mine sites.The results of this research can be used to promote the safe exploitation of deep coal mines and the exploitation of methane resources in coalbeds.
基金supported by the National Natural Science Foundation of China (Grant No. 40806043)
文摘The paper presents the design and preliminary test results of a corer used for hard seafloor sediments sampling. Generally the sediment cores are provided by either gravity-type coting or deep-ocean drilling for a range of studies. However, in consideration of the operability and available sample length in collecting hard sediments, these methods exhibit no advantages. In this paper, a new corer which can exploit both hydrostatic energy and gravity energy for hard sediments coting is presented. The hydrostatic energy is provided by pressure differential between ambient seawater pressure and air pressure in an empty cavity. During sampling process, the corer penetrates into the sediment like a gravity corer and then automatically shifts to the percussion mode. The experiments in the laboratory indicate that the corer can complete 40 cycles in the sea with a cycle time of 2.8 seconds in percussion mode and impact the sample tube with the velocity of 0.2 m/s during each cycle. Besides, its adjustable falling velocity can make the corer achieve the maximum efficiency in coring different sediments.
基金financially supported by the National Natural Science Foundation of China(Nos.42272153 and 42472195)the Research Fund of PetroChina Tarim Oilfield Company(No.671023060003)the Research Fund of China National Petroleum Corporation Limited(No.2023ZZ16YJ04).
文摘Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression and permeability tests to investigate the mechanical and seepage properties of tight sandstone.A digital core of tight sandstone was built using Computed Tomography(CT)scanning,which was divided into matrix and pore phases by a pore equivalent diameter threshold.A fluid-solid coupling model was established to investigate the seepage characteristics at micro-scale.The results showed that increasing the confining pressure decreased porosity,permeability,and flow velocity,with the pore phase becoming the dominant seepage channel.Cracks and large pores closed first under increasing pressure,resulted in a steep drop in permeability.However,permeability slightly decreased under high confining pressure,which followed a first-order exponential function.Flow velocity increased with seepage pressure.And the damage mainly occurred in stress-concentration regions under low seepage pressure.Seepage behavior followed linear Darcy flow,the damage emerged at seepage entrances under high pressure,which decreased rock elastic modulus and significantly increased permeability.
基金supported by the National Natural Science Foundation of China(Nos.51827901,42477191,and 52304033)the Fundamental Research Funds for the Central Universities(No.YJ202449)+1 种基金the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(No.SKLGME022009)the China Postdoctoral Science Foundation(No.2023M742446).
文摘Gas content serves as a critical indicator for assessing the resource potential of deep coal mines and forecasting coal mine gas outburst risks.However,existing sampling technologies face challenges in maintaining the integrity of gas content within samples and are often constrained by estimation errors inherent in empirical formulas,which results in inaccurate gas content measurements.This study introduces a lightweight,in-situ pressure-and gas-preserved corer designed to collect coal samples under the pressure conditions at the sampling point,effectively preventing gas loss during transfer and significantly improving measurement accuracy.Additionally,a gas migration model for deep coal mines was developed to elucidate gas migration characteristics under pressure-preserved coring conditions.The model offers valuable insights for optimizing coring parameters,demonstrating that both minimizing the coring hole diameter and reducing the pressure difference between the coring-point pressure and the original pore pressure can effectively improve the precision of gas content measurements.Coring tests conducted at an experimental base validated the performance of the corer and its effectiveness in sample collection.Furthermore,successful horizontal coring tests conducted in an underground coal mine roadway demonstrated that the measured gas content using pressure-preserved coring was 34%higher than that obtained through open sampling methods.
