Addressing the issues of significant entry settlement and severe mining pressure manifestations in the conventional 121 approach,an innovative N00 approach is proposed.By comparing the mining process and entry formati...Addressing the issues of significant entry settlement and severe mining pressure manifestations in the conventional 121 approach,an innovative N00 approach is proposed.By comparing the mining process and entry formation process of different approaches,the characteristics of entry roof settlement evolution under different approaches are obtained.The N00 approach,which incorporates roof cutting and NPR cable support,optimizes the mining and entry formation process to reduce the settlement phase of entry roof,decreases the settlement of entry roof,and enhances the steadiness of entry roof.The N00 approach modifies the entry roof structure through roof cutting and establishes a hydraulic support load mechanics model for the mining panel to derive the theoretical load pressure formula for the N00 approach’s hydraulic support.Compared with the conventional 121 approach,the pressure on the N00 approach’s hydraulic support is reduced.Empirical data obtained through field monitoring demonstrate that the N00 approach has reduced the roof settlement of the entry and weakened the mining pressure manifestation at the mining panel,achieving the goal of protecting the entry and mining panel.展开更多
In this study, a three dimensional(3D) numerical model of six-degrees-of-freedom(6DOF) is applied to simulate the water entries of twin spheres side-by-side at different lateral distances and time intervals.The turbul...In this study, a three dimensional(3D) numerical model of six-degrees-of-freedom(6DOF) is applied to simulate the water entries of twin spheres side-by-side at different lateral distances and time intervals.The turbulence structure is described using the shear-stress transport k-ω(SST k-ω) model, and the volume of fluid(VOF) method is used to track the complex air-liquid interface. The motion of spheres during water entry is simulated using an independent overset grid. The numerical model is verified by comparing the cavity evolution results from simulations and experiments. Numerical results reveal that the time interval between the twin water entries evidently affects cavity expansion and contraction behaviors in the radial direction. However, this influence is significantly weakened by increasing the lateral distance between the two spheres. In synchronous water entries, pressure is reduced on the midline of two cavities during surface closure, which is directly related to the cavity volume. The evolution of vortexes inside the two cavities is analyzed using a velocity vector field, which is affected by the lateral distance and time interval of water entries.展开更多
New solid backfill mining technology provides unique technical advantages for ‘‘three-under'' coal mining which refers to coal resources trapped under buildings, railways, and water bodies. This technology h...New solid backfill mining technology provides unique technical advantages for ‘‘three-under'' coal mining which refers to coal resources trapped under buildings, railways, and water bodies. This technology has a much higher recovery rate and can effectively control the surface subsidence. However, successful application of this technology depends heavily on geological conditions. To avoid the disadvantages associated with downward mining and overhead backfilling with this new technology, a new advanced solid backfill mining design with two pre-driving entries is proposed here to ensure the backfill effect. Taking Huayuan coal mine as an example, this paper tests the double gob-side entries retaining with no pillar left scheme and optimizes an integrated technology setup for backfill mining and gob-side entry retaining. Field applications show that the recovery rate increased from 40% for strip mining to 85% for backfill mining. Moreover, the new backfill technology allowed for better control over the surrounding rock deformation caused by the gob-side entry retaining effect and better control of ground subsidence as compared to strip mining.展开更多
This contribution describes development and application of a user-friendly finite element program,UT3PC, to address three important problems in underground coal mine design:(1) safety of main entries,(2) barrier pilla...This contribution describes development and application of a user-friendly finite element program,UT3PC, to address three important problems in underground coal mine design:(1) safety of main entries,(2) barrier pillar size needed for entry protection, and(3) safety of bleeder entries during the advance of an adjacent longwall panel.While the finite element method is by far the most popular engineering design tool of the digital age, widespread use by the mining community has been impeded by the relatively high cost of and the need for lengthy specialized training in numerical methods.Implementation of UT3PC overcomes these impediments in three easy steps.First, a material properties file is prepared for the considered site.Next, mesh generation is automatic through an interactive process.A third and last step is simply execution of the program.Examples using data from several western coal mines illustrate the ease of using the application for analysis of main entries, barrier pillars, and bleeder entry safety.展开更多
Based on a large amount of field investigation and observations, the paper analyzes and summarizes the mining depths and depth distribution of coal mines in China, discusses the characteristics of undrground pressure ...Based on a large amount of field investigation and observations, the paper analyzes and summarizes the mining depths and depth distribution of coal mines in China, discusses the characteristics of undrground pressure appearance in the entries of deep mining, points out some characteristics of surtounding rocks when rHo> =0.5, such as obvious rheologital deformation,and puts forward the main principles of supporting the entries in deep mining展开更多
Evaluation for blast resistances of rice entries of 20th to 23rd International Rice Blast Nursery (IRBN) was conducted at CNRRI during 1990-1993. The resistance to seedling blast (SB) was evaluated in a greenhouse at ...Evaluation for blast resistances of rice entries of 20th to 23rd International Rice Blast Nursery (IRBN) was conducted at CNRRI during 1990-1993. The resistance to seedling blast (SB) was evaluated in a greenhouse at 3-4 leaf stage with artificial inoculation while resistance to leaf blast (LB) and neck blast (NB) were evaluated in the natural field as instructed by the International Network of Genetic Evaluation for Rice (INGER). Materials with high level of blast resistance and good agronomic traits were selected and展开更多
In the study of thin-walled wedge shells subjected to lateral water entry impact loads,similarity theory is employed to predict the behavior of the prototype by analyzing the dynamic response of the model.However,the ...In the study of thin-walled wedge shells subjected to lateral water entry impact loads,similarity theory is employed to predict the behavior of the prototype by analyzing the dynamic response of the model.However,the traditional similarity law for structural impact fails to accurately describe the relationship between the dynamic responses of the model and the prototype,mainly due to the ignoring of the fluid-structure coupling effect and geometric distortion in the thickness direction.To address this limitation,this study employs dimensional analysis to derive the scaling factors for achieving structural similarity during water entry while considering the effects of fluid-structure coupling.Based on the analysis of the governing equations for thin-walled wedge shells under water entry impact loads,the scaling factor accounting for geometric distortion for water entry of wedge shells is determined.Numerical models are established to verify the applicability of the geometric distortion similarity model with different materials.The results demonstrate the effectiveness of the proposed similarity model,which significantly reduces the disparities in displacement peaks and energy between the scaled model and the prototype.In addition,experimental platforms are constructed to further verify the proposed similarity model by performing vertical water entry tests on thickness-distorted and material-distorted specimens.展开更多
Inspired by Phil Benson＇s study on the relations between ethnocentrism and the China-related entries in the OED2, this paper attempts to further examine how the image of China, a so--called ＂peripheral object of Wes...Inspired by Phil Benson＇s study on the relations between ethnocentrism and the China-related entries in the OED2, this paper attempts to further examine how the image of China, a so--called ＂peripheral object of Western knowledge,＂ has been （ntis-） constructed in the dictionary, particularly its latest 2009 CD-ROM version, into which many laudable updates, including corrections and supplements, have been meticulously incorporated. It argues that （ 1 ） although British imperialism was a closed chapter, its vestiges can still be spotted in the dictionary text, not only in the quotations, which preserve historical information rather than reflect the editors＇ opinions, but also in the definitions and notes, which betray primarily the thoughts of these editors, （ 2 ） to an average user, the OED, with its legendary philological authority, is very likely to project ＂ historical objectivity＂ into some problematic contents and thus misleads an innocent and uninformed mind, and （3） if ethnocentrism is an unavoidable component in the OED1 and OED2, then the editorial team of the OED3 in the making would do well to introduce into their work an element of＂ ＂ entholocalism,＂ by which is meant the ideological neutrality as well as the technical accuracy of encyclopedic information about such important peripheral objects as China, the most populous country and a fast growing economy, in the world in which the English language against the backdrop of globalization has firmly established itself as the international lingua fianca without rival. So long as it is intended to remain a historical dictionary true to its name, the OED ought to push forward, in the form of new editions, with the times.展开更多
Metabolic-associated fatty liver disease(MAFLD)is the most prevalent chronic liver disease globally,with no effective pharmacological treatments available for early-stage cases.Rutin,a bioactive flavonoid from Sophora...Metabolic-associated fatty liver disease(MAFLD)is the most prevalent chronic liver disease globally,with no effective pharmacological treatments available for early-stage cases.Rutin,a bioactive flavonoid from Sophora japonica L.,exhibits diverse pharmacological effects,but its multi-pathway mechanisms in improving MAFLD remain unclear.In this study,we employed a high-fat diet(HFD)-induced MAFLD mouse model to investigate the therapeutic effects of rutin supplementation.Rutin supplementation significantly reduced blood lipid and liver lipid levels and alleviated liver injury in MAFLD model mice.Fecal microbiota transplantation experiments revealed that rutin alleviated MAFLD by modulating the gut microbiota composition.Through 16S rRNA sequencing analysis and non-targeted metabolomics analysis of the normal control(NC),HFD and rutin groups,rutin was found to alter key species(Ruminococcus torques)and associated metabolites(e.g.,7-dehydrocholesterol,short-chain fatty acids),suggesting a mechanism involving the gut microbiota.Antibiotic treatment experiments revealed that rutin alleviates MAFLD via the blood entry pathway.Network pharmacology analysis showed that rutin can directly act on targets closely related to MAFLD development,including tumor protein p53,epidermal growth factor receptor,and prostaglandin-endoperoxide synthase 2,as well as key signaling pathways such as PI3K/AKT and MAPK.Transcriptomics analysis of the NC,HFD and rutin groups revealed that rutin may ameliorate MAFLD through PI3K/AKT and MAPK signaling pathways,which might be enhanced by the gut microbiota and blood entry pathways.In conclusion,rutin can treat MAFLD through both the gut microbiota and blood entry pathways,resulting in a synergistic effect.Our study provides a novel strategy for evaluating functional food components and offers a scientific basis for dietary flavonoid-based interventions against MAFLD.展开更多
For ordinary tourists, simpler entry and exit procedures and a broader range of duty-free goods in Hainan create a better travel and shopping experience.For China’s earnest endeavor to deepen reform and opening-up, i...For ordinary tourists, simpler entry and exit procedures and a broader range of duty-free goods in Hainan create a better travel and shopping experience.For China’s earnest endeavor to deepen reform and opening-up, implementation of the special customs operations policy in Hainan represents a significant step forward. For businesses in Malaysia and other ASEAN member states, especially export-oriented small and medium-sized enterprises (SMEs), Hainan serves as a“transit hub” for accessing the Chinese market and even other Asian markets.展开更多
As a core functional refractory in the continuous casting process,the service reliability of the submerged entry nozzle(SEN)is directly related to the stability of continuous casting production,the quality of casting ...As a core functional refractory in the continuous casting process,the service reliability of the submerged entry nozzle(SEN)is directly related to the stability of continuous casting production,the quality of casting billets,and production efficiency.Al_(2)O_(3) inclusions clogging constitutes the predominant failure mode of SEN,particularly during continuous casting of high-grade steels.Although several studies in the literature have demonstrated that electric field application can mitigate SEN clogging to some extent,the underlying mechanism remains poorly understood,which hinders its widespread acceptance and practical implementation.The mechanism of preventing SEN clogging by applying a positive electric field was studied,and experimental verification was conducted on it in a certain steel plant.The results indicate that Al_(2)O_(3) inclusions exhibit a positive charge in molten steel under high-temperature(~1600℃)and low-oxygen-partial-pressure(≤20×10-6)conditions.In the continuous casting process at a Chinese steel plant,applying a positive electric field to the SEN effectively suppressed the migration of Al_(2)O_(3) inclusions toward the SEN wall,significantly enhancing its clogging resistance.展开更多
The refractory composition of submerged entry nozzles(SEN)critically governs interfacial reactions,which in turn determines the onset of clogging.The interfacial reactions between two Al_(2)O_(3)-C refractories with 8...The refractory composition of submerged entry nozzles(SEN)critically governs interfacial reactions,which in turn determines the onset of clogging.The interfacial reactions between two Al_(2)O_(3)-C refractories with 8.7 and 1.7 Al_(2)O_(3)/SiO_(2)ratios and Al-killed steel were studied through laboratory experiments.The flow of molten steel relative to the inner wall of the SEN was simulated by rotating a refractory rod in high-temperature molten steel.For the Al_(2)O_(3)-C refractory with an 8.7 Al_(2)O_(3)/SiO_(2)ratio,an Al_(2)O_(3)reaction layer was formed at the steel/refractory interface as the reaction progressed,which initially grew to 780μm before thinning to 470μm.Concurrently,the refractory surface became entirely coated with both clustered and plate-shaped Al_(2)O_(3)inclusions following 120 min of reaction.For the Al_(2)O_(3)-C refractory with a 1.7 Al_(2)O_(3)/SiO_(2)ratio,a continuous Si-Al-Fe-O liquid reaction layer was generated at the steel/refractory interface,which significantly impeded the physicochemical interactions between the molten steel and refractory.The composition of the reaction layer evolved sequentially from the Si-Al-Fe-O liquid phase to the Si-Al-O solid phases with the increasing reaction time.After 120 min,the refractory surface became fully coated with clustered Al_(2)O_(3)inclusions.Compared to the Al_(2)O_(3)-C refractory with a 1.7 Al_(2)O_(3)/SiO_(2)ratio,the Al_(2)O_(3)-C refractory with an 8.7 Al_(2)O_(3)/SiO_(2)ratio was more likely to capture Al_(2)O_(3)inclusions in the steel during its contact with Al-killed steel.The current experiment results indicate that in Al-killed steel continuous casting operations,Al_(2)O_(3)-C-based SEN with an 8.7 Al_(2)O_(3)/SiO_(2)ratio should have a higher clogging potential than Al_(2)O_(3)-C-based SEN with a 1.7 Al_(2)O_(3)/SiO_(2)ratio under equivalent casting conditions.展开更多
Let(g_(n))_(n≥1) be a sequence of independent and identically distributed positive random d×d matrices and consider the matrix product G_(n)=g_(n)…g_1.Under suitable conditions,we establish the Berry-Esseen bou...Let(g_(n))_(n≥1) be a sequence of independent and identically distributed positive random d×d matrices and consider the matrix product G_(n)=g_(n)…g_1.Under suitable conditions,we establish the Berry-Esseen bounds on the rate of convergence in the central limit theorem and Cramer-type moderate deviation expansions,for any matrix norm ‖G_(n)‖ of G_(n),its entries G_(n)^(i,j) and its spectral radius ρ(G_(n)).Extended versions of their joint law with the direction of the random walk G_(n)x are also established,where x is a starting point in the unit sphere of R~d.展开更多
The reaction of carbon-free oxide-based(corundum,spinel,zirconia,and mullite)submerged entry nozzle(SEN)lining with rare earth inclusions and its anti-clogging effects under near working conditions were systematically...The reaction of carbon-free oxide-based(corundum,spinel,zirconia,and mullite)submerged entry nozzle(SEN)lining with rare earth inclusions and its anti-clogging effects under near working conditions were systematically studied.A variety of lining composite test methods were innovatively used to ensure the consistency of test conditions.The experimental results showed that the mullite(acidic oxide)has strong reactivity with rare earth inclusions,and the spinel(basic oxide)has stable chemical properties and weak reactivity with rare earth inclusions.Because alumina is one of the main reactants of clogging formation,corundum is not suitable for SEN lining.There are less clogs on the surface of zirconia,but it will be exsoluted and unstable.Therefore,solving the problem of zirconia exsolution will greatly strengthen its application in SEN lining.展开更多
The study aims to explore the damage characteristics and protection technologies of liquid-filled structures under high-speed projectile impact.A series of penetration impact experiments were conducted by focusing on ...The study aims to explore the damage characteristics and protection technologies of liquid-filled structures under high-speed projectile impact.A series of penetration impact experiments were conducted by focusing on different air layer configurations.By using high-speed camera and dynamic measurement systems,the effects of air layers on the projectile penetration,pressure wave propagation,cavitation evolution,and structural dynamic responses were analyzed.The results showed that the rarefaction wave reflected from the air-liquid interface significantly reduced the peak and specific impulse of the initial pressure wave,thereby diminishing the impact load on the structure.Additionally,the compressibility of air layers also attenuated the cavitation extrusion load.Both front and rear plates exhibited superimposed deformation modes,i.e.,local deformation or petal fracture with global deformation.Air layers effectively mitigated global deformation.However,when the air layer was positioned on the projectile's trajectory,it split the water-entry process and velocity attenuation of the projectile into two relatively independent phases.And the secondary water entry pressure wave caused more severe local deformation and petal fractures on the rear plate.展开更多
Stromal interaction molecules(STIM)s are Ca^(2+)sensors in internal Ca^(2+)stores of the endoplasmic reticulum.They activate the store-operated Ca^(2+)channels,which are the main source of Ca^(2+)entry in non-excitabl...Stromal interaction molecules(STIM)s are Ca^(2+)sensors in internal Ca^(2+)stores of the endoplasmic reticulum.They activate the store-operated Ca^(2+)channels,which are the main source of Ca^(2+)entry in non-excitable cells.Moreover,STIM proteins interact with other Ca^(2+)channel subunits and active transporters,making STIMs an important intermediate molecule in orchestrating a wide variety of Ca^(2+)influxes into excitable cells.Nevertheless,little is known about the role of STIM proteins in brain functioning.Being involved in many signaling pathways,STIMs replenish internal Ca^(2+)stores in neurons and mediate synaptic transmission and neuronal excitability.Ca^(2+)dyshomeostasis is a signature of many pathological conditions of the brain,including neurodegenerative diseases,injuries,stroke,and epilepsy.STIMs play a role in these disturbances not only by supporting abnormal store-operated Ca^(2+)entry but also by regulating Ca^(2+)influx through other channels.Here,we review the present knowledge of STIMs in neurons and their involvement in brain pathology.展开更多
Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,...Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.展开更多
To enhance the recuperation rate of the mine and comply with the stipulations of green mining technology, it is vital to expeditiously recuperate the coal pillar resources in the final stage, thus preventing the consi...To enhance the recuperation rate of the mine and comply with the stipulations of green mining technology, it is vital to expeditiously recuperate the coal pillar resources in the final stage, thus preventing the considerable squandering of resources. The coal pillar resource of the main roadway and its branch roadway constitutes a significant recovery subject. Its coal pillar shape is regular and possesses a considerable strike distance, facilitating the arrangement of the coal pillar recovery working face (CPRWF) for mining operations. However, for the remaining coal pillars with a thick and hard roof (THF) and multiple tectonic zones, CPRWF encounters challenges in selecting an appropriate layout, managing excessive roof pressure, and predicting mining stress. Aiming at the roadway coal pillar group with THF and multi-structural areas in specific projects, a method of constructing multi-stage CPRWF by one side gob-side entry driving (GSED) and one side roadway reusing is proposed. Through theoretical calculation of roof fracture and numerical simulation verification, combined with field engineering experience and economic analysis, the width of the narrow coal pillar (NCP) in the GSED is determined to be 10 m and the length of the CPRWF is 65 m. Concurrently, the potential safety hazard that the roof will fall asymmetrically and THF is difficult to break during CPRWF mining after GSED is analyzed and verified. Then, a control method involving the pre-cutting of the roof in the reused roadway before mining is proposed. This method has been shown to facilitate the complete collapse of THF, reduce the degree of mine pressure, and facilitate the symmetrical breaking of the roof. Accordingly, a roof-cutting scheme based on a directional drilling rig, bidirectional shaped polyvinyl chloride (PVC) pipe, and emulsion explosive was devised, and the pre-splitting of 8.2 m THF was accomplished. Field observations indicate that directional cracks are evident in the roof, the coal wall is flat during CPRWF mining, and the overall level of mining pressure is within the control range. Therefore, the combined application of GSED and roof-cutting technology for coal pillar recovery has been successfully implemented, thereby providing new insights and engineering references for the construction and pressure relief mining of CPRWF.展开更多
基金Project(2022XDHZ12)supported by the Lvliang Technology Project,ChinaProjects(8232056,2232080)supported by the Beijing Natural Science Foundation,ChinaProject([2020]3008)supported by the Science and Technology Projects in Guizhou Province,China。
文摘Addressing the issues of significant entry settlement and severe mining pressure manifestations in the conventional 121 approach,an innovative N00 approach is proposed.By comparing the mining process and entry formation process of different approaches,the characteristics of entry roof settlement evolution under different approaches are obtained.The N00 approach,which incorporates roof cutting and NPR cable support,optimizes the mining and entry formation process to reduce the settlement phase of entry roof,decreases the settlement of entry roof,and enhances the steadiness of entry roof.The N00 approach modifies the entry roof structure through roof cutting and establishes a hydraulic support load mechanics model for the mining panel to derive the theoretical load pressure formula for the N00 approach’s hydraulic support.Compared with the conventional 121 approach,the pressure on the N00 approach’s hydraulic support is reduced.Empirical data obtained through field monitoring demonstrate that the N00 approach has reduced the roof settlement of the entry and weakened the mining pressure manifestation at the mining panel,achieving the goal of protecting the entry and mining panel.
基金China Academy of Launch Vehicle Technology(Grant No.CALT-2022-03)Science and Technology on Underwater Information and Control Laboratory(Grant No.2021-JCJQ-LB-030-05).
文摘In this study, a three dimensional(3D) numerical model of six-degrees-of-freedom(6DOF) is applied to simulate the water entries of twin spheres side-by-side at different lateral distances and time intervals.The turbulence structure is described using the shear-stress transport k-ω(SST k-ω) model, and the volume of fluid(VOF) method is used to track the complex air-liquid interface. The motion of spheres during water entry is simulated using an independent overset grid. The numerical model is verified by comparing the cavity evolution results from simulations and experiments. Numerical results reveal that the time interval between the twin water entries evidently affects cavity expansion and contraction behaviors in the radial direction. However, this influence is significantly weakened by increasing the lateral distance between the two spheres. In synchronous water entries, pressure is reduced on the midline of two cavities during surface closure, which is directly related to the cavity volume. The evolution of vortexes inside the two cavities is analyzed using a velocity vector field, which is affected by the lateral distance and time interval of water entries.
基金supported by the Fundamental Research Funds program for the Central Universities (No. 2014RC02)the Research Innovation Program for College Graduates of Jiangsu Province (No. CXLX13_951)Qing Lan Project
文摘New solid backfill mining technology provides unique technical advantages for ‘‘three-under'' coal mining which refers to coal resources trapped under buildings, railways, and water bodies. This technology has a much higher recovery rate and can effectively control the surface subsidence. However, successful application of this technology depends heavily on geological conditions. To avoid the disadvantages associated with downward mining and overhead backfilling with this new technology, a new advanced solid backfill mining design with two pre-driving entries is proposed here to ensure the backfill effect. Taking Huayuan coal mine as an example, this paper tests the double gob-side entries retaining with no pillar left scheme and optimizes an integrated technology setup for backfill mining and gob-side entry retaining. Field applications show that the recovery rate increased from 40% for strip mining to 85% for backfill mining. Moreover, the new backfill technology allowed for better control over the surrounding rock deformation caused by the gob-side entry retaining effect and better control of ground subsidence as compared to strip mining.
文摘This contribution describes development and application of a user-friendly finite element program,UT3PC, to address three important problems in underground coal mine design:(1) safety of main entries,(2) barrier pillar size needed for entry protection, and(3) safety of bleeder entries during the advance of an adjacent longwall panel.While the finite element method is by far the most popular engineering design tool of the digital age, widespread use by the mining community has been impeded by the relatively high cost of and the need for lengthy specialized training in numerical methods.Implementation of UT3PC overcomes these impediments in three easy steps.First, a material properties file is prepared for the considered site.Next, mesh generation is automatic through an interactive process.A third and last step is simply execution of the program.Examples using data from several western coal mines illustrate the ease of using the application for analysis of main entries, barrier pillars, and bleeder entry safety.
文摘Based on a large amount of field investigation and observations, the paper analyzes and summarizes the mining depths and depth distribution of coal mines in China, discusses the characteristics of undrground pressure appearance in the entries of deep mining, points out some characteristics of surtounding rocks when rHo> =0.5, such as obvious rheologital deformation,and puts forward the main principles of supporting the entries in deep mining
文摘Evaluation for blast resistances of rice entries of 20th to 23rd International Rice Blast Nursery (IRBN) was conducted at CNRRI during 1990-1993. The resistance to seedling blast (SB) was evaluated in a greenhouse at 3-4 leaf stage with artificial inoculation while resistance to leaf blast (LB) and neck blast (NB) were evaluated in the natural field as instructed by the International Network of Genetic Evaluation for Rice (INGER). Materials with high level of blast resistance and good agronomic traits were selected and
基金supported by the National Natural Science Foundation of China(Grant Nos.11972309,12272320 and 12272309)the Overseas Expertise Introduction Project for Discipline Innovation(the 111 Project)(Grant No.BP0719007).
文摘In the study of thin-walled wedge shells subjected to lateral water entry impact loads,similarity theory is employed to predict the behavior of the prototype by analyzing the dynamic response of the model.However,the traditional similarity law for structural impact fails to accurately describe the relationship between the dynamic responses of the model and the prototype,mainly due to the ignoring of the fluid-structure coupling effect and geometric distortion in the thickness direction.To address this limitation,this study employs dimensional analysis to derive the scaling factors for achieving structural similarity during water entry while considering the effects of fluid-structure coupling.Based on the analysis of the governing equations for thin-walled wedge shells under water entry impact loads,the scaling factor accounting for geometric distortion for water entry of wedge shells is determined.Numerical models are established to verify the applicability of the geometric distortion similarity model with different materials.The results demonstrate the effectiveness of the proposed similarity model,which significantly reduces the disparities in displacement peaks and energy between the scaled model and the prototype.In addition,experimental platforms are constructed to further verify the proposed similarity model by performing vertical water entry tests on thickness-distorted and material-distorted specimens.
文摘Inspired by Phil Benson＇s study on the relations between ethnocentrism and the China-related entries in the OED2, this paper attempts to further examine how the image of China, a so--called ＂peripheral object of Western knowledge,＂ has been （ntis-） constructed in the dictionary, particularly its latest 2009 CD-ROM version, into which many laudable updates, including corrections and supplements, have been meticulously incorporated. It argues that （ 1 ） although British imperialism was a closed chapter, its vestiges can still be spotted in the dictionary text, not only in the quotations, which preserve historical information rather than reflect the editors＇ opinions, but also in the definitions and notes, which betray primarily the thoughts of these editors, （ 2 ） to an average user, the OED, with its legendary philological authority, is very likely to project ＂ historical objectivity＂ into some problematic contents and thus misleads an innocent and uninformed mind, and （3） if ethnocentrism is an unavoidable component in the OED1 and OED2, then the editorial team of the OED3 in the making would do well to introduce into their work an element of＂ ＂ entholocalism,＂ by which is meant the ideological neutrality as well as the technical accuracy of encyclopedic information about such important peripheral objects as China, the most populous country and a fast growing economy, in the world in which the English language against the backdrop of globalization has firmly established itself as the international lingua fianca without rival. So long as it is intended to remain a historical dictionary true to its name, the OED ought to push forward, in the form of new editions, with the times.
基金funded by the Natural Science Foundation of Shandong Province(ZR2023MH263)the China Postdoctoral Science Foundation(2023M733918,2023T160729)the Central Government Guidance Foundation for Local Science and Technology Development(YDZX2024133).
文摘Metabolic-associated fatty liver disease(MAFLD)is the most prevalent chronic liver disease globally,with no effective pharmacological treatments available for early-stage cases.Rutin,a bioactive flavonoid from Sophora japonica L.,exhibits diverse pharmacological effects,but its multi-pathway mechanisms in improving MAFLD remain unclear.In this study,we employed a high-fat diet(HFD)-induced MAFLD mouse model to investigate the therapeutic effects of rutin supplementation.Rutin supplementation significantly reduced blood lipid and liver lipid levels and alleviated liver injury in MAFLD model mice.Fecal microbiota transplantation experiments revealed that rutin alleviated MAFLD by modulating the gut microbiota composition.Through 16S rRNA sequencing analysis and non-targeted metabolomics analysis of the normal control(NC),HFD and rutin groups,rutin was found to alter key species(Ruminococcus torques)and associated metabolites(e.g.,7-dehydrocholesterol,short-chain fatty acids),suggesting a mechanism involving the gut microbiota.Antibiotic treatment experiments revealed that rutin alleviates MAFLD via the blood entry pathway.Network pharmacology analysis showed that rutin can directly act on targets closely related to MAFLD development,including tumor protein p53,epidermal growth factor receptor,and prostaglandin-endoperoxide synthase 2,as well as key signaling pathways such as PI3K/AKT and MAPK.Transcriptomics analysis of the NC,HFD and rutin groups revealed that rutin may ameliorate MAFLD through PI3K/AKT and MAPK signaling pathways,which might be enhanced by the gut microbiota and blood entry pathways.In conclusion,rutin can treat MAFLD through both the gut microbiota and blood entry pathways,resulting in a synergistic effect.Our study provides a novel strategy for evaluating functional food components and offers a scientific basis for dietary flavonoid-based interventions against MAFLD.
文摘For ordinary tourists, simpler entry and exit procedures and a broader range of duty-free goods in Hainan create a better travel and shopping experience.For China’s earnest endeavor to deepen reform and opening-up, implementation of the special customs operations policy in Hainan represents a significant step forward. For businesses in Malaysia and other ASEAN member states, especially export-oriented small and medium-sized enterprises (SMEs), Hainan serves as a“transit hub” for accessing the Chinese market and even other Asian markets.
基金supported by the National Outstanding Youth Science Fund Project of National Natural Science Foundation of China(No.52302031)National Natural Science Foundation of China(No.51932008).
文摘As a core functional refractory in the continuous casting process,the service reliability of the submerged entry nozzle(SEN)is directly related to the stability of continuous casting production,the quality of casting billets,and production efficiency.Al_(2)O_(3) inclusions clogging constitutes the predominant failure mode of SEN,particularly during continuous casting of high-grade steels.Although several studies in the literature have demonstrated that electric field application can mitigate SEN clogging to some extent,the underlying mechanism remains poorly understood,which hinders its widespread acceptance and practical implementation.The mechanism of preventing SEN clogging by applying a positive electric field was studied,and experimental verification was conducted on it in a certain steel plant.The results indicate that Al_(2)O_(3) inclusions exhibit a positive charge in molten steel under high-temperature(~1600℃)and low-oxygen-partial-pressure(≤20×10-6)conditions.In the continuous casting process at a Chinese steel plant,applying a positive electric field to the SEN effectively suppressed the migration of Al_(2)O_(3) inclusions toward the SEN wall,significantly enhancing its clogging resistance.
基金support from the National Key R&D Program(Grant No.2023YFB3709901)the National Natural Science Foundation of China(Grant Nos.U22A20171,52474366 and 52404335)the High Steel Center(HSC)at North China University of Technology.
文摘The refractory composition of submerged entry nozzles(SEN)critically governs interfacial reactions,which in turn determines the onset of clogging.The interfacial reactions between two Al_(2)O_(3)-C refractories with 8.7 and 1.7 Al_(2)O_(3)/SiO_(2)ratios and Al-killed steel were studied through laboratory experiments.The flow of molten steel relative to the inner wall of the SEN was simulated by rotating a refractory rod in high-temperature molten steel.For the Al_(2)O_(3)-C refractory with an 8.7 Al_(2)O_(3)/SiO_(2)ratio,an Al_(2)O_(3)reaction layer was formed at the steel/refractory interface as the reaction progressed,which initially grew to 780μm before thinning to 470μm.Concurrently,the refractory surface became entirely coated with both clustered and plate-shaped Al_(2)O_(3)inclusions following 120 min of reaction.For the Al_(2)O_(3)-C refractory with a 1.7 Al_(2)O_(3)/SiO_(2)ratio,a continuous Si-Al-Fe-O liquid reaction layer was generated at the steel/refractory interface,which significantly impeded the physicochemical interactions between the molten steel and refractory.The composition of the reaction layer evolved sequentially from the Si-Al-Fe-O liquid phase to the Si-Al-O solid phases with the increasing reaction time.After 120 min,the refractory surface became fully coated with clustered Al_(2)O_(3)inclusions.Compared to the Al_(2)O_(3)-C refractory with a 1.7 Al_(2)O_(3)/SiO_(2)ratio,the Al_(2)O_(3)-C refractory with an 8.7 Al_(2)O_(3)/SiO_(2)ratio was more likely to capture Al_(2)O_(3)inclusions in the steel during its contact with Al-killed steel.The current experiment results indicate that in Al-killed steel continuous casting operations,Al_(2)O_(3)-C-based SEN with an 8.7 Al_(2)O_(3)/SiO_(2)ratio should have a higher clogging potential than Al_(2)O_(3)-C-based SEN with a 1.7 Al_(2)O_(3)/SiO_(2)ratio under equivalent casting conditions.
基金supported by Deutsche Forschungsgemeinschaft (DFG) (Grant No. ME 4473/2-1)the Centre Henri Lebesgue (CHL) (Grant No. ANR-11-LABX-0020-01)National Natural Science Foundation of China (Grants Nos. 11971063, 11731012, 12271062 and 12288201)。
文摘Let(g_(n))_(n≥1) be a sequence of independent and identically distributed positive random d×d matrices and consider the matrix product G_(n)=g_(n)…g_1.Under suitable conditions,we establish the Berry-Esseen bounds on the rate of convergence in the central limit theorem and Cramer-type moderate deviation expansions,for any matrix norm ‖G_(n)‖ of G_(n),its entries G_(n)^(i,j) and its spectral radius ρ(G_(n)).Extended versions of their joint law with the direction of the random walk G_(n)x are also established,where x is a starting point in the unit sphere of R~d.
基金supported by the National Outstanding Youth Science Fund Project of National Natural Science Foundation of China(52302031)National Natural Science Foundation of China(51932008 and 51772277)Central China Thousand Talents Project(204200510011).
文摘The reaction of carbon-free oxide-based(corundum,spinel,zirconia,and mullite)submerged entry nozzle(SEN)lining with rare earth inclusions and its anti-clogging effects under near working conditions were systematically studied.A variety of lining composite test methods were innovatively used to ensure the consistency of test conditions.The experimental results showed that the mullite(acidic oxide)has strong reactivity with rare earth inclusions,and the spinel(basic oxide)has stable chemical properties and weak reactivity with rare earth inclusions.Because alumina is one of the main reactants of clogging formation,corundum is not suitable for SEN lining.There are less clogs on the surface of zirconia,but it will be exsoluted and unstable.Therefore,solving the problem of zirconia exsolution will greatly strengthen its application in SEN lining.
基金the financial support provided by National Natural Science Foundation of China(Grant Nos.52271338,52371342 and 51979277).
文摘The study aims to explore the damage characteristics and protection technologies of liquid-filled structures under high-speed projectile impact.A series of penetration impact experiments were conducted by focusing on different air layer configurations.By using high-speed camera and dynamic measurement systems,the effects of air layers on the projectile penetration,pressure wave propagation,cavitation evolution,and structural dynamic responses were analyzed.The results showed that the rarefaction wave reflected from the air-liquid interface significantly reduced the peak and specific impulse of the initial pressure wave,thereby diminishing the impact load on the structure.Additionally,the compressibility of air layers also attenuated the cavitation extrusion load.Both front and rear plates exhibited superimposed deformation modes,i.e.,local deformation or petal fracture with global deformation.Air layers effectively mitigated global deformation.However,when the air layer was positioned on the projectile's trajectory,it split the water-entry process and velocity attenuation of the projectile into two relatively independent phases.And the secondary water entry pressure wave caused more severe local deformation and petal fractures on the rear plate.
基金supported by grants from the Russian Science Foundation(23-44-00054)the National Natural Science Foundation of China(32261133525).
文摘Stromal interaction molecules(STIM)s are Ca^(2+)sensors in internal Ca^(2+)stores of the endoplasmic reticulum.They activate the store-operated Ca^(2+)channels,which are the main source of Ca^(2+)entry in non-excitable cells.Moreover,STIM proteins interact with other Ca^(2+)channel subunits and active transporters,making STIMs an important intermediate molecule in orchestrating a wide variety of Ca^(2+)influxes into excitable cells.Nevertheless,little is known about the role of STIM proteins in brain functioning.Being involved in many signaling pathways,STIMs replenish internal Ca^(2+)stores in neurons and mediate synaptic transmission and neuronal excitability.Ca^(2+)dyshomeostasis is a signature of many pathological conditions of the brain,including neurodegenerative diseases,injuries,stroke,and epilepsy.STIMs play a role in these disturbances not only by supporting abnormal store-operated Ca^(2+)entry but also by regulating Ca^(2+)influx through other channels.Here,we review the present knowledge of STIMs in neurons and their involvement in brain pathology.
基金supported by the Fundamental Research Funds for the Central Universities(No.FRF-BD-23-01).
文摘Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.
基金Project(52204164) supported by the National Natural Science Foundation of ChinaProject(2023ZKPYSB01) supported by the Fundamental Research Funds for the Central Universities,China。
文摘To enhance the recuperation rate of the mine and comply with the stipulations of green mining technology, it is vital to expeditiously recuperate the coal pillar resources in the final stage, thus preventing the considerable squandering of resources. The coal pillar resource of the main roadway and its branch roadway constitutes a significant recovery subject. Its coal pillar shape is regular and possesses a considerable strike distance, facilitating the arrangement of the coal pillar recovery working face (CPRWF) for mining operations. However, for the remaining coal pillars with a thick and hard roof (THF) and multiple tectonic zones, CPRWF encounters challenges in selecting an appropriate layout, managing excessive roof pressure, and predicting mining stress. Aiming at the roadway coal pillar group with THF and multi-structural areas in specific projects, a method of constructing multi-stage CPRWF by one side gob-side entry driving (GSED) and one side roadway reusing is proposed. Through theoretical calculation of roof fracture and numerical simulation verification, combined with field engineering experience and economic analysis, the width of the narrow coal pillar (NCP) in the GSED is determined to be 10 m and the length of the CPRWF is 65 m. Concurrently, the potential safety hazard that the roof will fall asymmetrically and THF is difficult to break during CPRWF mining after GSED is analyzed and verified. Then, a control method involving the pre-cutting of the roof in the reused roadway before mining is proposed. This method has been shown to facilitate the complete collapse of THF, reduce the degree of mine pressure, and facilitate the symmetrical breaking of the roof. Accordingly, a roof-cutting scheme based on a directional drilling rig, bidirectional shaped polyvinyl chloride (PVC) pipe, and emulsion explosive was devised, and the pre-splitting of 8.2 m THF was accomplished. Field observations indicate that directional cracks are evident in the roof, the coal wall is flat during CPRWF mining, and the overall level of mining pressure is within the control range. Therefore, the combined application of GSED and roof-cutting technology for coal pillar recovery has been successfully implemented, thereby providing new insights and engineering references for the construction and pressure relief mining of CPRWF.
