The methane drainage can not only make coal seams deformation, but also effect its stress distribution. Based on lab experiment on methane drainage with a cubic coal sample of 500 mm×500 mm×500 mm, mutative ...The methane drainage can not only make coal seams deformation, but also effect its stress distribution. Based on lab experiment on methane drainage with a cubic coal sample of 500 mm×500 mm×500 mm, mutative law of coal of pore pressure （p） and effective stress （σef）i were investigated during methane drainage with the coal sample of China Lu＇an coal field No.3 coal seam. The experiment results indicate： during methane drainage pore pressure （p） follows exponential attenuation law： p=aexp（-bt）; effective stress （σef）i of coal masses follows logarithm incremental law： （σef）,=aln t＋b, （i=x, y, z）; effective stress coefficient（a） follows logarithm attenuation law： a=a-bln t; effective stress coefficient, volume stress （Θef） and pore pressure （p） follow bilinear law.展开更多
Helium sorption cooler technology is a key means to realize highly reliable low-vibration very lowtemperature environments,which have important applications in fields such as quantum computing and space exploration.Th...Helium sorption cooler technology is a key means to realize highly reliable low-vibration very lowtemperature environments,which have important applications in fields such as quantum computing and space exploration.The laboratory designed a superfluid suppression small hole and a multi-ribbed condenser,developed a reliable-performance helium sorption cooler(HSC),and conducted experimental studies.Experimental results show that the prototype can achieve the lowest cooling temperature of 873 mK without load by filling 6MPa helium at room temperature.The low-temperature hold time is 26 h,and the temperature fluctuation is within 0.8 mK.The cooling power of the helium sorption cooler is 1 mW@0.98 K@3.5 h.Experimental results indicate that when the charging pressure is reduced to 4MPa,theminimum temperature decreases to 836mK,and the hold time shortens to 16 h.When the pre-cooling temperature increases from 3.9 to 4.9 K,the hold time is reduced to 3 h.展开更多
Ultrahigh-performance concrete(UHPC)is a groundbreaking kind of concrete that distinguishes itself from conventional concrete through its unique material properties.Understanding and managing the time-dependent charac...Ultrahigh-performance concrete(UHPC)is a groundbreaking kind of concrete that distinguishes itself from conventional concrete through its unique material properties.Understanding and managing the time-dependent characteristics of these materials is essential for their effective use in various construction applications.This study presents an experimental evaluation of the compressive and bending properties of the UHPC incorporating polypropylene,steel,and glass fibers.Based on ACI-211 guidelines,the UHPC mix was designed by using three types of aggregates:limestone,andesite,and quartzite,along with 5%fiber content(at varying percentages of 0,5%,10%,15%,and 20%)relative to the cementitious materials,and three different water-to-cement(w/c)ratios(0.24,0.3,and 0.4)were used.In this research,the compressive and flexural strength tests were conducted.The results show that increasing the values of the fibers significantly enhances the compressive strength of the studied samples.Furthermore,the utilization of fibers markedly improves the bending strength of the samples,demonstrating a strong correlation with the yield resistance of the material.Also,findings show that using steel fibers increases the compressive and bending strength of the tested samples more than polypropylene and glass fibers.For instance,in UHPC samples with 0.4 w/c,the average compressive strength values are 82.2 MPa,70.3 MPa,and 67.1 MPa for steel,polypropylene,and glass fibers,respectively.Also,in the flexural strength test,the modulus of rupture is obtained as an average of 6.24 MPa,5.24 MPa and 4.83 MPa for UHPC samples with steel,polypropylene and glass fibers,respectively.展开更多
BACKGROUND IgE plays a critical role in allergic inflammation and asthma pathogenesis.This study investigates the involvement of IgE cells in asthma exacerbation and evaluates the effectiveness of targeted interventio...BACKGROUND IgE plays a critical role in allergic inflammation and asthma pathogenesis.This study investigates the involvement of IgE cells in asthma exacerbation and evaluates the effectiveness of targeted interventions.AIM To evaluate the role of IgE in the exacerbation of allergic asthma and to determine the clinical efficacy of anti-IgE therapy in improving disease outcomes.Specifically,the study investigates changes in serum IgE levels,lung function,asthma control scores,and the frequency of acute exacerbations among patients receiving standard therapy with or without anti-IgE intervention.METHODS A total of 200 patients diagnosed with moderate to severe asthma were enrolled in this experimental study conducted from April 2024 to April 2025.Participants were randomized to receive either standard asthma therapy or therapy combined with anti-IgE agents.IgE levels and asthma control parameters were monitored.RESULTS Participants receiving anti-IgE treatment demonstrated a significant reduction in serum IgE levels(P<0.001),improved Forced expiratory volume in one second scores,and fewer exacerbation episodes compared to the control group.CONCLUSION IgE cells significantly contribute to asthma severity,and targeted therapy against IgE can improve disease outcomes.These findings underscore the importance of immunomodulatory strategies in asthma management.展开更多
This study aimed to evaluate the feasibility,safety,and efficacy of a noveltranscatheter suture closure system(HaloStitch^(®))for patent foramen ovale(PFO)closure in a swine model.Methods:Thirteen swine underwent...This study aimed to evaluate the feasibility,safety,and efficacy of a noveltranscatheter suture closure system(HaloStitch^(®))for patent foramen ovale(PFO)closure in a swine model.Methods:Thirteen swine underwentexperimental PF0 model creation.All animals received implantationof the transcatheter suture closure system to evaluate procedural success.Comprehensive follow-up over sixmonths included serial ultrasound imaging,histopathological analysis,and gross anatomical exaninationof cardiac specimens.Results:Successful HaloStitch^(®)device implantation was adhieved in 11 of 13 swine.Gross anatomical examination confirrned secure positioning of all sutures in the atrial septum,with noredundancy or thrombus formation.Postoperative ultrasound demonstrated stable suture and staplepositions throughout follow-up,with no evidence of suture breakage,displacement,or thrombus.Stapleswere clearly visualized under ultrasound imaging,Both the atrial septal defect orifice diameter and residualseptal shunt flow velocity decreased significantly during the observation period.Histopathological analysisrevealed partially organized thrombi at the implant head and fibrous connective tissue encapsulation withlocalized inflammatory cell infiltration surrounding the polymer material.Conclsions:The transcathetersuture closure system(HaloStitch^(®))demonstrated feasibility,safety,and biocompatib ility for PFO closure ina swine model,supporting its potential for clinical translation.展开更多
Low damping characteristics have always been a key sticking points in the development of gas bearings.The application of squeeze film dampers can significantly improve the damping performance of gas lubricated bearing...Low damping characteristics have always been a key sticking points in the development of gas bearings.The application of squeeze film dampers can significantly improve the damping performance of gas lubricated bearings.This paper proposed a novel hermetic diaphragm squeeze film damper(HDSFD)for oil-free turbomachinery supported by gas lubricated bearings.Several types of HDSFDs with symmetrical structure were proposed for good damping performance.By considering the compressibility of the damper fluid,based on hydraulic fluid mechanics theory,a dynamic model of HDSFDs under medium is proposed,which successfully reflects the frequency dependence of force coefficients.Based on the dynamic model,the effects of damper fluid viscosity,bulk modulus of damper fluid,thickness of damper fluid film and plunger thickness on the dynamic stiffness and damping of HDSFDs were analyzed.An experimental test rig was assembled and series of experimental studies on HDSFDs were conducted.The damper fluid transverse flow is added to the existing HDSFD concept,which aims to make the dynamic force coefficients independent of frequency.Although the force coefficient is still frequency dependent,the damping coefficient at high frequency excitation with damper fluid supply twice as that without damper fluid supply.The results serve as a benchmark for the calibration of analytical tools under development.展开更多
In this paper,experimental and numerical studies of heat transfer in a test local of side H=0.8 m heated from below are presented and compared.All the walls,the rest of the floor and the ceiling are made from plywood ...In this paper,experimental and numerical studies of heat transfer in a test local of side H=0.8 m heated from below are presented and compared.All the walls,the rest of the floor and the ceiling are made from plywood and polystyrene in sandwich form(3 mmplywood-3 cm polystyrene-3 mmplywood)just on one of the vertical walls contained a glazed door(2 H/3×0.15 m).This local is heated during two heating cycles by a square plate of iron the width L=0.6 H,which represents the heat source,its temperature T_(h) is controlled.The plate is heated for two cycles by an adjustable set-point heat source placed just down the center of it.For each cycle,the heat source is switched“on”for 6 h and switched“off”for 6 h.The outdoor air temperature is kept constant at a low temperature T_(c)<T_(h).All measurements are carried out with k-type thermocouples and with flux meters.Results will be qualitatively presented for two cycles of heating in terms of temperatures and heat flux densitiesϕfor various positions of the test local.The temperature evolution of the center and the profile of the temperature along the vertical centerline are compared by two dimensions simulation using the lattice Boltzmann method.The comparison shows a good agreement with a difference that does not exceed±1℃.展开更多
In the scenario of a steam generator tube rupture accident in a lead-cooled fast reactor,secondary circuit subcooled water under high pressure is injected into an ordinary-pressure primary vessel,where a molten lead-b...In the scenario of a steam generator tube rupture accident in a lead-cooled fast reactor,secondary circuit subcooled water under high pressure is injected into an ordinary-pressure primary vessel,where a molten lead-based alloy(typically pure lead or lead-bismuth eutectic(LBE))is used as the coolant.To clarify the pressure build-up characteristics under water-jet injection,this study conducted several experiments by injecting pressurized water into a molten LBE pool at Sun Yat-sen University.To obtain a further understanding,several new experimental parameters were adopted,including the melt temperature,water subcooling,injection pressure,injection duration,and nozzle diameter.Through detailed analyses,it was found that the pressure and temperature during the water-melt interaction exhibited a consistent variation trend with our previous water-droplet injection mode LBE experiment.Similarly,the existence of a steam explosion was confirmed,which typically results in a much stronger pressure build-up.For the non-explosion cases,increasing the injection pressure,melt-pool temperature,nozzle diameter,and water subcooling promoted pressure build-up in the melt pool.However,a limited enhancement effect was observed when increasing the injection duration,which may be owing to the continually rising pressure in the interaction vessel or the isolation effect of the generated steam cavity.Regardless of whether a steam explosion occurred,the calculated mechanical and kinetic energy conversion efficiencies of the melt were relatively small(not exceeding 4.1%and 0.7%,respectively).Moreover,the range of the conversion efficiency was similar to that of previous water-droplet experiments,although the upper limit of the jet mode was slightly lower.展开更多
This study aimed to investigate the moment redistribution in continuous glass fiber reinforced polymer(GFRP)-concrete composite slabs caused by concrete cracking and steel bar yielding in the negative bending moment z...This study aimed to investigate the moment redistribution in continuous glass fiber reinforced polymer(GFRP)-concrete composite slabs caused by concrete cracking and steel bar yielding in the negative bending moment zone.An experimental bending moment redistribution test was conducted on continuous GFRP-concrete composite slabs,and a calculation method based on the conjugate beam method was proposed.The composite slabs were formed by combining GFRP profiles with a concrete layer and supported on steel beams to create two-span continuous composite slab specimens.Two methods,epoxy resin bonding,and stud connection,were used to connect the composite slabs with the steel beams.The experimental findings showed that the specimen connected with epoxy resin exhibited two moments redistribution phenomena during the loading process:concrete cracking and steel bar yielding at the internal support.In contrast,the composite slab connected with steel beams by studs exhibited only one-moment redistribution phenomenon throughout the loading process.As the concrete at the internal support cracked,the bending moment decreased in the internal support section and increased in the midspan section.When the steel bars yielded,the bending moment further decreased in the internal support section and increased in the mid-span section.Since GFRP profiles do not experience cracking,there was no significant decrease in the bending moment of the mid-span section.All test specimens experienced compressive failure of concrete at the mid-span section.Calculation results showed good agreement between the calculated and experimental values of bending moments in the mid-span section and internal support section.The proposed model can effectively predict the moment redistribution behavior of continuous GFRP-concrete composite slabs.展开更多
The detonation of fuel-rich explosives yields combustible products that persistently burn upon mixing with ambient oxygen,releasing additional energy through a phenomenon known as the afterburning effect.This process ...The detonation of fuel-rich explosives yields combustible products that persistently burn upon mixing with ambient oxygen,releasing additional energy through a phenomenon known as the afterburning effect.This process greatly influences the evolution of confined blast loading and the subsequent structural response,which is crucial in confined blast scenarios.Given the complex nature of the reaction process,accurate analysis of the afterburning effect remains challenging.Previous studies have either overlooked the mechanisms of detonation product combustion or failed to provide experimental validation.This study introduces a three-dimensional model to effectively characterize the combustion of detonation products.The model integrates chemical reaction source terms into the governing equations to consider the combustion processes.Numerical simulations and experimental tests were conducted to analyze the combustion and energy release from the detonation products of fuel-rich explosives in confined spaces.Approximately 50%of the energy was released during the combustion of detonation products in a confined TNT explosion.Although the combustion of these products was much slower than the detonation process,it aligned with the dynamic response of the structure,which enhanced the explosive yield.Excluding afterburning from the analysis reduced the center-point deformation of the structure by 30%.Following the inclusion of afterburning,the simulated quasistatic pressure increased by approximately 45%.Subsequent comparisons highlighted the merits of the proposed approach over conventional methods.This approach eliminates the reliance on empirical parameters,such as the amount and rate of energy release during afterburning,thereby laying the foundation for understanding load evolution in more complex environments,such as ships,buildings,and underground tunnels.展开更多
Stripping injection overcomes the limitations of Liouville's theorem and is widely used for beam injection and accumulation in high-intensity synchrotrons.The interaction between the stripping foil and beam is cru...Stripping injection overcomes the limitations of Liouville's theorem and is widely used for beam injection and accumulation in high-intensity synchrotrons.The interaction between the stripping foil and beam is crucial in the study of stripping injection,particularly in low-energy stripping injection synchrotrons,such as the XiPAF synchrotron.The foil thickness is the main parameter that affects the properties of the beam after injection.The thin stripping foil is reinforced with collodion during its installation.However,the collodion on the foil surface makes it difficult to determine its equivalent thickness,because the mechanical measurements are not sufficiently reliable or convenient for continuously determining foil thickness.We propose an online stripping foil thickness measurement method based on the ionization energy loss effect,which is suitable for any foil thickness and does not require additional equipment.Experimental studies were conducted using the XiPAF synchrotron.The limitation of this method was examined,and the results were verified by comparing the experimentally obtained beam current accumulation curves with the simulation results.This confirms the accuracy and reliability of the proposed method for measuring the stripping foil thickness.展开更多
Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance.However,despite their resistance to temperature fluctuations a...Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance.However,despite their resistance to temperature fluctuations and environmental aggressors,silicone elastomers exhibit relatively low stiffness,limiting their direct applicability in seismic isolation.This study investigates the effect of fumed silica as a reinforcing filler to enhance the mechanical properties of laminated silicone elastomeric bearings.Elastomeric samples were fabricated with varying fumed silica proportions and subjected to Shore A hardness,uniaxial tensile,and lap shear tests to assess the influence of filler content.Additionally,quasi-static tests were conducted on reduced-scale bearing prototypes under combined vertical compression and cyclic horizontal shear to evaluate their seismic isolation performance.The results demonstrate that fumed silica reinforcement significantly increases stiffness,as evidenced by higher Shore A hardness values.However,a trade-off was observed in tensile properties,with reductions in tensile strength and elongation at break.Despite this,the equivalent elastic modulus did not show substantial variation up to large deformations,indicating that stiffness is preserved under most working conditions.Lap shear tests showed that fumed silica improves shear resistance,while quasi-static tests revealed inelastic behavior with small increases in equivalent shear coefficients but no substantial loss in damping ratios.These findings suggest that fumed silica reinforcement enhances silicone elastomers’stiffness and shear resistance while maintaining moderate damping properties,making it a promising approach for improving the mechanical performance of elastomeric bearings in seismic isolation applications.展开更多
Experimental study on the fundamental behavior of box shape steel reinforced concrete （SRC） beams was conducted. Seven 1 ： 3 scale model SRC beams were tested to failure. The experimental results indicate that the ...Experimental study on the fundamental behavior of box shape steel reinforced concrete （SRC） beams was conducted. Seven 1 ： 3 scale model SRC beams were tested to failure. The experimental results indicate that the flexural strength increases with the increase of the ratio of flexural reinforcement and the thickness of flange of the shape steel; the shear strength increases with the increase in the thickness of the web of the shape steel. Concrete filled in the box shape steel can prevent the early failure of specimens due to the buckling of the box shape steel, and increase the ultimate load. Measures should be made to strengthen the connection and co-work between the shape steel and the concrete. Formulae for flexural and shear strength of the composite beams are proposed, and the calculated results are in good agreement with the experimental results. In general, the box shape SRC beam is a kind of ductile member, and it is suitable for extensive engineering application.展开更多
In this study the effect of Sheng-ai Injection i.e. Red Ginseng-Ophiopogon Root Injection (one kind of traditional Chinese medicines) on the contractivity of diaphragm was observed. The results confirmed that Sheng-ai...In this study the effect of Sheng-ai Injection i.e. Red Ginseng-Ophiopogon Root Injection (one kind of traditional Chinese medicines) on the contractivity of diaphragm was observed. The results confirmed that Sheng-ai Injection increased Pdi of the fatigued diaphragm in rabbits and reduced the time needed for the recovery of Pdi of fatigued diaphragm to the normal value. These results suggest that Sheng-Mai Injection can increase the contractive force and promote the recovery of the fatigued diaphragm. The effect of Sheng-ai Injection on the contractivity of the isolated diaphragmatic bundle of rats was also observed and the results confirmed that Sheng-ai Injection increased the diaphragmatic contractive force directly. This effect of increasing the contractive force of diaphragm was attenuated by adding calcium channel blocker isoptin and disappeared when there was no calcium in the extracellular fluid. It is deduced, therefore, that the mechanism of the effect of Sheng-mai Injection is related to the increased influx of calcium from extracellular fluid into the cells.展开更多
Beam-column or beam-wall connections are an important problem in high-rise buildings. In this study, based on the analysis of an example structure, an analytical model for design of the semi-rigid connections between ...Beam-column or beam-wall connections are an important problem in high-rise buildings. In this study, based on the analysis of an example structure, an analytical model for design of the semi-rigid connections between steel beams and RC walls in high-rise hybrid buildings is proposed. Also, the mechanical characteristics of these connections subjected to low-reversed cyclic loading are investigated through comparison of experimental results from three semi-rigid connections and two rigid connections. Moreover, some latent problems for design of these connections as well as the corresponding solutions are discussed. The results from the experiments and analyses indicate that semi-rigid connections exhibit satisfactory capacity and seismic performance, and the proposed design can be used in practice.展开更多
Mixed gases (CO 2 and CH 4 etc .) in different ratio under the action of transient electric field may cause temperature to increase about 6℃, while under that of solar irradiation may lead temperature to rise a...Mixed gases (CO 2 and CH 4 etc .) in different ratio under the action of transient electric field may cause temperature to increase about 6℃, while under that of solar irradiation may lead temperature to rise around 3℃. The temperature increasing mechanism of satellitic thermo infrared of lower air is explained here based on an experimental study: thermo infrared temperature increasing of lower atmosphere may be caused by paroxysmal releasing of crustal gas and sudden changing of lower atmosphere electrostatic field. Therefore, appearance of the anomaly of thermo infrared temperature increasing prior to a moderate strong earthquake requires the concurrence of gas paroxysmal releasing and electrostatic field sudden changing at the same time.展开更多
Ten full-scale steel beam-to-column moment connections used in moment-resisting frames （MRFs） were tested to study the failure process, failure mode, strength and plastic rotation capacity. The specimens include one...Ten full-scale steel beam-to-column moment connections used in moment-resisting frames （MRFs） were tested to study the failure process, failure mode, strength and plastic rotation capacity. The specimens include one traditional welded flange-bolted web connection, one traditional fully welded connection, four beam flange strengthened connections, three beam flange weakened connections, and one through-diaphragm connection. The test results show that the connections with flange cover plates or with partly cut beam flanges satisfy the beam plastic rotation demand for ductile MRFs. From the measured stress profiles along the beam flange and beam web depth, the mechanics of brittle fracture at the end of the beam is discussed. Design recommendations for steel beam-to-column moment connections are proposed.展开更多
At present,methods for treating tertiary oil recovery wastewater via electro-coagulation are still in their early stage of development.In this study,a device for electro-coagulation wastewater treatment was built and ...At present,methods for treating tertiary oil recovery wastewater via electro-coagulation are still in their early stage of development.In this study,a device for electro-coagulation wastewater treatment was built and tested in an oil field.The effects that the initial pH value,electrode type,and connection mode have on the coagulation and separation effect were assessed by measuring the mass fraction and turbidity of oil.The results have shown that when the electro-coagulation method is used,the effectiveness of the treatment can be significantly increased in neutral pH conditions(pH=7),in acidic conditions,and in alkaline conditions.Compared to an Al electrode,the floc that is produced by an Fe electrode is smaller;thus,it does not easily coagulate and settle in a short time.Using the oil removal rate,turbidity removal rate and energy consumption as a basis to assess the performances,the results have demonstrated that the combined aluminum alloy iron composite electrode should be used as electrolytic electrode.展开更多
A liquid sloshing experimental rig driven by a wave-maker is designed and built to study liquid sloshing problems in a rectangular liquid tank with perforated baffle. A series of experiments are conducted in this expe...A liquid sloshing experimental rig driven by a wave-maker is designed and built to study liquid sloshing problems in a rectangular liquid tank with perforated baffle. A series of experiments are conducted in this experimental rig to estimate the free surface fluctuation and pressure distribution by changing external excitation frequency of the shaking table. An in-house CFD code is also used in this study to simulate the liquid sloshing in three-dimensional （3D） rectangular tank with perforated baffle. Good agreements of free surface elevation and pressure between the numerical results and the experimental data are obtained and presented. Spectral analysis of the time history of free surface elevation is conducted by using the fast Fourier transformation.展开更多
基金Supported by the National Natural Science Foundation of China（50404017） the Natural Science Foundation for Young Scientists of Shanxi Province, China （20051026）
文摘The methane drainage can not only make coal seams deformation, but also effect its stress distribution. Based on lab experiment on methane drainage with a cubic coal sample of 500 mm×500 mm×500 mm, mutative law of coal of pore pressure （p） and effective stress （σef）i were investigated during methane drainage with the coal sample of China Lu＇an coal field No.3 coal seam. The experiment results indicate： during methane drainage pore pressure （p） follows exponential attenuation law： p=aexp（-bt）; effective stress （σef）i of coal masses follows logarithm incremental law： （σef）,=aln t＋b, （i=x, y, z）; effective stress coefficient（a） follows logarithm attenuation law： a=a-bln t; effective stress coefficient, volume stress （Θef） and pore pressure （p） follow bilinear law.
基金supported by the Hundred Talents Programof the Chinese Academy of Sciences,the Pre-Research Project JZX7Y20220414101801the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB35000000)the National Natural Science Foundation Projects(No.51806231).
文摘Helium sorption cooler technology is a key means to realize highly reliable low-vibration very lowtemperature environments,which have important applications in fields such as quantum computing and space exploration.The laboratory designed a superfluid suppression small hole and a multi-ribbed condenser,developed a reliable-performance helium sorption cooler(HSC),and conducted experimental studies.Experimental results show that the prototype can achieve the lowest cooling temperature of 873 mK without load by filling 6MPa helium at room temperature.The low-temperature hold time is 26 h,and the temperature fluctuation is within 0.8 mK.The cooling power of the helium sorption cooler is 1 mW@0.98 K@3.5 h.Experimental results indicate that when the charging pressure is reduced to 4MPa,theminimum temperature decreases to 836mK,and the hold time shortens to 16 h.When the pre-cooling temperature increases from 3.9 to 4.9 K,the hold time is reduced to 3 h.
文摘Ultrahigh-performance concrete(UHPC)is a groundbreaking kind of concrete that distinguishes itself from conventional concrete through its unique material properties.Understanding and managing the time-dependent characteristics of these materials is essential for their effective use in various construction applications.This study presents an experimental evaluation of the compressive and bending properties of the UHPC incorporating polypropylene,steel,and glass fibers.Based on ACI-211 guidelines,the UHPC mix was designed by using three types of aggregates:limestone,andesite,and quartzite,along with 5%fiber content(at varying percentages of 0,5%,10%,15%,and 20%)relative to the cementitious materials,and three different water-to-cement(w/c)ratios(0.24,0.3,and 0.4)were used.In this research,the compressive and flexural strength tests were conducted.The results show that increasing the values of the fibers significantly enhances the compressive strength of the studied samples.Furthermore,the utilization of fibers markedly improves the bending strength of the samples,demonstrating a strong correlation with the yield resistance of the material.Also,findings show that using steel fibers increases the compressive and bending strength of the tested samples more than polypropylene and glass fibers.For instance,in UHPC samples with 0.4 w/c,the average compressive strength values are 82.2 MPa,70.3 MPa,and 67.1 MPa for steel,polypropylene,and glass fibers,respectively.Also,in the flexural strength test,the modulus of rupture is obtained as an average of 6.24 MPa,5.24 MPa and 4.83 MPa for UHPC samples with steel,polypropylene and glass fibers,respectively.
文摘BACKGROUND IgE plays a critical role in allergic inflammation and asthma pathogenesis.This study investigates the involvement of IgE cells in asthma exacerbation and evaluates the effectiveness of targeted interventions.AIM To evaluate the role of IgE in the exacerbation of allergic asthma and to determine the clinical efficacy of anti-IgE therapy in improving disease outcomes.Specifically,the study investigates changes in serum IgE levels,lung function,asthma control scores,and the frequency of acute exacerbations among patients receiving standard therapy with or without anti-IgE intervention.METHODS A total of 200 patients diagnosed with moderate to severe asthma were enrolled in this experimental study conducted from April 2024 to April 2025.Participants were randomized to receive either standard asthma therapy or therapy combined with anti-IgE agents.IgE levels and asthma control parameters were monitored.RESULTS Participants receiving anti-IgE treatment demonstrated a significant reduction in serum IgE levels(P<0.001),improved Forced expiratory volume in one second scores,and fewer exacerbation episodes compared to the control group.CONCLUSION IgE cells significantly contribute to asthma severity,and targeted therapy against IgE can improve disease outcomes.These findings underscore the importance of immunomodulatory strategies in asthma management.
基金supported by grants from National High-Level Hospital Clinical Research Funding(2023-GSP-RC-04).
文摘This study aimed to evaluate the feasibility,safety,and efficacy of a noveltranscatheter suture closure system(HaloStitch^(®))for patent foramen ovale(PFO)closure in a swine model.Methods:Thirteen swine underwentexperimental PF0 model creation.All animals received implantationof the transcatheter suture closure system to evaluate procedural success.Comprehensive follow-up over sixmonths included serial ultrasound imaging,histopathological analysis,and gross anatomical exaninationof cardiac specimens.Results:Successful HaloStitch^(®)device implantation was adhieved in 11 of 13 swine.Gross anatomical examination confirrned secure positioning of all sutures in the atrial septum,with noredundancy or thrombus formation.Postoperative ultrasound demonstrated stable suture and staplepositions throughout follow-up,with no evidence of suture breakage,displacement,or thrombus.Stapleswere clearly visualized under ultrasound imaging,Both the atrial septal defect orifice diameter and residualseptal shunt flow velocity decreased significantly during the observation period.Histopathological analysisrevealed partially organized thrombi at the implant head and fibrous connective tissue encapsulation withlocalized inflammatory cell infiltration surrounding the polymer material.Conclsions:The transcathetersuture closure system(HaloStitch^(®))demonstrated feasibility,safety,and biocompatib ility for PFO closure ina swine model,supporting its potential for clinical translation.
基金Supported by National Key Research and Development Program of China (Grant No.2021YFF0600208)National Natural Science Foundation of China (Grant No.52005170)Hunan Provincial Science and Technology Innovation Program of China (Grant No.2020RC4018)。
文摘Low damping characteristics have always been a key sticking points in the development of gas bearings.The application of squeeze film dampers can significantly improve the damping performance of gas lubricated bearings.This paper proposed a novel hermetic diaphragm squeeze film damper(HDSFD)for oil-free turbomachinery supported by gas lubricated bearings.Several types of HDSFDs with symmetrical structure were proposed for good damping performance.By considering the compressibility of the damper fluid,based on hydraulic fluid mechanics theory,a dynamic model of HDSFDs under medium is proposed,which successfully reflects the frequency dependence of force coefficients.Based on the dynamic model,the effects of damper fluid viscosity,bulk modulus of damper fluid,thickness of damper fluid film and plunger thickness on the dynamic stiffness and damping of HDSFDs were analyzed.An experimental test rig was assembled and series of experimental studies on HDSFDs were conducted.The damper fluid transverse flow is added to the existing HDSFD concept,which aims to make the dynamic force coefficients independent of frequency.Although the force coefficient is still frequency dependent,the damping coefficient at high frequency excitation with damper fluid supply twice as that without damper fluid supply.The results serve as a benchmark for the calibration of analytical tools under development.
文摘In this paper,experimental and numerical studies of heat transfer in a test local of side H=0.8 m heated from below are presented and compared.All the walls,the rest of the floor and the ceiling are made from plywood and polystyrene in sandwich form(3 mmplywood-3 cm polystyrene-3 mmplywood)just on one of the vertical walls contained a glazed door(2 H/3×0.15 m).This local is heated during two heating cycles by a square plate of iron the width L=0.6 H,which represents the heat source,its temperature T_(h) is controlled.The plate is heated for two cycles by an adjustable set-point heat source placed just down the center of it.For each cycle,the heat source is switched“on”for 6 h and switched“off”for 6 h.The outdoor air temperature is kept constant at a low temperature T_(c)<T_(h).All measurements are carried out with k-type thermocouples and with flux meters.Results will be qualitatively presented for two cycles of heating in terms of temperatures and heat flux densitiesϕfor various positions of the test local.The temperature evolution of the center and the profile of the temperature along the vertical centerline are compared by two dimensions simulation using the lattice Boltzmann method.The comparison shows a good agreement with a difference that does not exceed±1℃.
基金supported by Basic and Applied Basic research foundation of Guangdong province(Nos.2021A1515010343 and 2022A1515011582)the Science and Technology Program of Guangdong Province(Nos.2021A0505030026 and 2022A0505050029).
文摘In the scenario of a steam generator tube rupture accident in a lead-cooled fast reactor,secondary circuit subcooled water under high pressure is injected into an ordinary-pressure primary vessel,where a molten lead-based alloy(typically pure lead or lead-bismuth eutectic(LBE))is used as the coolant.To clarify the pressure build-up characteristics under water-jet injection,this study conducted several experiments by injecting pressurized water into a molten LBE pool at Sun Yat-sen University.To obtain a further understanding,several new experimental parameters were adopted,including the melt temperature,water subcooling,injection pressure,injection duration,and nozzle diameter.Through detailed analyses,it was found that the pressure and temperature during the water-melt interaction exhibited a consistent variation trend with our previous water-droplet injection mode LBE experiment.Similarly,the existence of a steam explosion was confirmed,which typically results in a much stronger pressure build-up.For the non-explosion cases,increasing the injection pressure,melt-pool temperature,nozzle diameter,and water subcooling promoted pressure build-up in the melt pool.However,a limited enhancement effect was observed when increasing the injection duration,which may be owing to the continually rising pressure in the interaction vessel or the isolation effect of the generated steam cavity.Regardless of whether a steam explosion occurred,the calculated mechanical and kinetic energy conversion efficiencies of the melt were relatively small(not exceeding 4.1%and 0.7%,respectively).Moreover,the range of the conversion efficiency was similar to that of previous water-droplet experiments,although the upper limit of the jet mode was slightly lower.
基金supported by National Natural Science Foundation of China(Project No.51878156,received by Wen-Wei Wang) and EPC Innovation Consulting Project for Longkou Nanshan LNG Phase I Receiving Terminal(Z2000LGENT0399,received by Wen-Wei Wang and ZhaoJun Zhang).
文摘This study aimed to investigate the moment redistribution in continuous glass fiber reinforced polymer(GFRP)-concrete composite slabs caused by concrete cracking and steel bar yielding in the negative bending moment zone.An experimental bending moment redistribution test was conducted on continuous GFRP-concrete composite slabs,and a calculation method based on the conjugate beam method was proposed.The composite slabs were formed by combining GFRP profiles with a concrete layer and supported on steel beams to create two-span continuous composite slab specimens.Two methods,epoxy resin bonding,and stud connection,were used to connect the composite slabs with the steel beams.The experimental findings showed that the specimen connected with epoxy resin exhibited two moments redistribution phenomena during the loading process:concrete cracking and steel bar yielding at the internal support.In contrast,the composite slab connected with steel beams by studs exhibited only one-moment redistribution phenomenon throughout the loading process.As the concrete at the internal support cracked,the bending moment decreased in the internal support section and increased in the midspan section.When the steel bars yielded,the bending moment further decreased in the internal support section and increased in the mid-span section.Since GFRP profiles do not experience cracking,there was no significant decrease in the bending moment of the mid-span section.All test specimens experienced compressive failure of concrete at the mid-span section.Calculation results showed good agreement between the calculated and experimental values of bending moments in the mid-span section and internal support section.The proposed model can effectively predict the moment redistribution behavior of continuous GFRP-concrete composite slabs.
基金supported by the National Natural Science Foundation of China(Grant Nos.52171318 and 12202329)Joint Foundation of the Ministry of Education(Grant No.8091B022105)。
文摘The detonation of fuel-rich explosives yields combustible products that persistently burn upon mixing with ambient oxygen,releasing additional energy through a phenomenon known as the afterburning effect.This process greatly influences the evolution of confined blast loading and the subsequent structural response,which is crucial in confined blast scenarios.Given the complex nature of the reaction process,accurate analysis of the afterburning effect remains challenging.Previous studies have either overlooked the mechanisms of detonation product combustion or failed to provide experimental validation.This study introduces a three-dimensional model to effectively characterize the combustion of detonation products.The model integrates chemical reaction source terms into the governing equations to consider the combustion processes.Numerical simulations and experimental tests were conducted to analyze the combustion and energy release from the detonation products of fuel-rich explosives in confined spaces.Approximately 50%of the energy was released during the combustion of detonation products in a confined TNT explosion.Although the combustion of these products was much slower than the detonation process,it aligned with the dynamic response of the structure,which enhanced the explosive yield.Excluding afterburning from the analysis reduced the center-point deformation of the structure by 30%.Following the inclusion of afterburning,the simulated quasistatic pressure increased by approximately 45%.Subsequent comparisons highlighted the merits of the proposed approach over conventional methods.This approach eliminates the reliance on empirical parameters,such as the amount and rate of energy release during afterburning,thereby laying the foundation for understanding load evolution in more complex environments,such as ships,buildings,and underground tunnels.
文摘Stripping injection overcomes the limitations of Liouville's theorem and is widely used for beam injection and accumulation in high-intensity synchrotrons.The interaction between the stripping foil and beam is crucial in the study of stripping injection,particularly in low-energy stripping injection synchrotrons,such as the XiPAF synchrotron.The foil thickness is the main parameter that affects the properties of the beam after injection.The thin stripping foil is reinforced with collodion during its installation.However,the collodion on the foil surface makes it difficult to determine its equivalent thickness,because the mechanical measurements are not sufficiently reliable or convenient for continuously determining foil thickness.We propose an online stripping foil thickness measurement method based on the ionization energy loss effect,which is suitable for any foil thickness and does not require additional equipment.Experimental studies were conducted using the XiPAF synchrotron.The limitation of this method was examined,and the results were verified by comparing the experimentally obtained beam current accumulation curves with the simulation results.This confirms the accuracy and reliability of the proposed method for measuring the stripping foil thickness.
文摘Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance.However,despite their resistance to temperature fluctuations and environmental aggressors,silicone elastomers exhibit relatively low stiffness,limiting their direct applicability in seismic isolation.This study investigates the effect of fumed silica as a reinforcing filler to enhance the mechanical properties of laminated silicone elastomeric bearings.Elastomeric samples were fabricated with varying fumed silica proportions and subjected to Shore A hardness,uniaxial tensile,and lap shear tests to assess the influence of filler content.Additionally,quasi-static tests were conducted on reduced-scale bearing prototypes under combined vertical compression and cyclic horizontal shear to evaluate their seismic isolation performance.The results demonstrate that fumed silica reinforcement significantly increases stiffness,as evidenced by higher Shore A hardness values.However,a trade-off was observed in tensile properties,with reductions in tensile strength and elongation at break.Despite this,the equivalent elastic modulus did not show substantial variation up to large deformations,indicating that stiffness is preserved under most working conditions.Lap shear tests showed that fumed silica improves shear resistance,while quasi-static tests revealed inelastic behavior with small increases in equivalent shear coefficients but no substantial loss in damping ratios.These findings suggest that fumed silica reinforcement enhances silicone elastomers’stiffness and shear resistance while maintaining moderate damping properties,making it a promising approach for improving the mechanical performance of elastomeric bearings in seismic isolation applications.
文摘Experimental study on the fundamental behavior of box shape steel reinforced concrete （SRC） beams was conducted. Seven 1 ： 3 scale model SRC beams were tested to failure. The experimental results indicate that the flexural strength increases with the increase of the ratio of flexural reinforcement and the thickness of flange of the shape steel; the shear strength increases with the increase in the thickness of the web of the shape steel. Concrete filled in the box shape steel can prevent the early failure of specimens due to the buckling of the box shape steel, and increase the ultimate load. Measures should be made to strengthen the connection and co-work between the shape steel and the concrete. Formulae for flexural and shear strength of the composite beams are proposed, and the calculated results are in good agreement with the experimental results. In general, the box shape SRC beam is a kind of ductile member, and it is suitable for extensive engineering application.
文摘In this study the effect of Sheng-ai Injection i.e. Red Ginseng-Ophiopogon Root Injection (one kind of traditional Chinese medicines) on the contractivity of diaphragm was observed. The results confirmed that Sheng-ai Injection increased Pdi of the fatigued diaphragm in rabbits and reduced the time needed for the recovery of Pdi of fatigued diaphragm to the normal value. These results suggest that Sheng-Mai Injection can increase the contractive force and promote the recovery of the fatigued diaphragm. The effect of Sheng-ai Injection on the contractivity of the isolated diaphragmatic bundle of rats was also observed and the results confirmed that Sheng-ai Injection increased the diaphragmatic contractive force directly. This effect of increasing the contractive force of diaphragm was attenuated by adding calcium channel blocker isoptin and disappeared when there was no calcium in the extracellular fluid. It is deduced, therefore, that the mechanism of the effect of Sheng-mai Injection is related to the increased influx of calcium from extracellular fluid into the cells.
基金National Natural Science Foundation of China Under Grant No. 50025821
文摘Beam-column or beam-wall connections are an important problem in high-rise buildings. In this study, based on the analysis of an example structure, an analytical model for design of the semi-rigid connections between steel beams and RC walls in high-rise hybrid buildings is proposed. Also, the mechanical characteristics of these connections subjected to low-reversed cyclic loading are investigated through comparison of experimental results from three semi-rigid connections and two rigid connections. Moreover, some latent problems for design of these connections as well as the corresponding solutions are discussed. The results from the experiments and analyses indicate that semi-rigid connections exhibit satisfactory capacity and seismic performance, and the proposed design can be used in practice.
文摘Mixed gases (CO 2 and CH 4 etc .) in different ratio under the action of transient electric field may cause temperature to increase about 6℃, while under that of solar irradiation may lead temperature to rise around 3℃. The temperature increasing mechanism of satellitic thermo infrared of lower air is explained here based on an experimental study: thermo infrared temperature increasing of lower atmosphere may be caused by paroxysmal releasing of crustal gas and sudden changing of lower atmosphere electrostatic field. Therefore, appearance of the anomaly of thermo infrared temperature increasing prior to a moderate strong earthquake requires the concurrence of gas paroxysmal releasing and electrostatic field sudden changing at the same time.
文摘Ten full-scale steel beam-to-column moment connections used in moment-resisting frames （MRFs） were tested to study the failure process, failure mode, strength and plastic rotation capacity. The specimens include one traditional welded flange-bolted web connection, one traditional fully welded connection, four beam flange strengthened connections, three beam flange weakened connections, and one through-diaphragm connection. The test results show that the connections with flange cover plates or with partly cut beam flanges satisfy the beam plastic rotation demand for ductile MRFs. From the measured stress profiles along the beam flange and beam web depth, the mechanics of brittle fracture at the end of the beam is discussed. Design recommendations for steel beam-to-column moment connections are proposed.
文摘At present,methods for treating tertiary oil recovery wastewater via electro-coagulation are still in their early stage of development.In this study,a device for electro-coagulation wastewater treatment was built and tested in an oil field.The effects that the initial pH value,electrode type,and connection mode have on the coagulation and separation effect were assessed by measuring the mass fraction and turbidity of oil.The results have shown that when the electro-coagulation method is used,the effectiveness of the treatment can be significantly increased in neutral pH conditions(pH=7),in acidic conditions,and in alkaline conditions.Compared to an Al electrode,the floc that is produced by an Fe electrode is smaller;thus,it does not easily coagulate and settle in a short time.Using the oil removal rate,turbidity removal rate and energy consumption as a basis to assess the performances,the results have demonstrated that the combined aluminum alloy iron composite electrode should be used as electrolytic electrode.
基金supported by the China Postdoctoral Science Foundation(Grant No.2012M511192)the National Natural Science Foundation of China(Grant Nos.51209080 and 51061130547+5 种基金Open Fund of State Key Laboratory of Coastaland Off shore Engineering(Grant No.LP1207the Open Fund of State Key Laboratory of Hydraulics and Mountain River Engineering(Grant No.1213)Qing Lan Project and 333 Project of Jiangsu Province(Grant No.BRA2012130)the Fundamental Research Funds for the Central Universities(Hohai University,Grant No.2012B06514the 111 Project(Grant No.B12032)Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120181110084)
文摘A liquid sloshing experimental rig driven by a wave-maker is designed and built to study liquid sloshing problems in a rectangular liquid tank with perforated baffle. A series of experiments are conducted in this experimental rig to estimate the free surface fluctuation and pressure distribution by changing external excitation frequency of the shaking table. An in-house CFD code is also used in this study to simulate the liquid sloshing in three-dimensional （3D） rectangular tank with perforated baffle. Good agreements of free surface elevation and pressure between the numerical results and the experimental data are obtained and presented. Spectral analysis of the time history of free surface elevation is conducted by using the fast Fourier transformation.
