As the bed depth increases,sintering yield increases,but the productivity decreases.To reveal the reasons for the decrease in productivity and explore targeted solutions,the bed resistance of mixtures,wet zone,and com...As the bed depth increases,sintering yield increases,but the productivity decreases.To reveal the reasons for the decrease in productivity and explore targeted solutions,the bed resistance of mixtures,wet zone,and combustion zone was analyzed in the laboratory.The results showed that the decreased porosity of mixture resulted in the increased bed resistance by 160.56%when the bed depth increased from 600 to 1000 mm.After improving porosity of 1%by adding loosening bars with optimized size and distribution,the bed resistance decreased,and the productivity increased by 5%.The increase in bed depth increased the thickness of the wet zone from 120 to 680 mm and the resistance from 1.56 to 8.83 kPa.By using a three-stage intensive mixer and pre-adding water for granulation,the moisture of mixture was reduced by 0.6%,and the sintering productivity increased by 4%.Besides,the high bed resistance is mainly caused by the increase in the thickness of the combustion zone from 31.9 to 132.7 mm,and the bed resistance increased from 0.70 to 5.62 kPa.The bed resistance of the combustion zone at 900 mm was increased by 90.51%compared to 700 mm.After optimization of the distribution of coke breeze,the thickness of combustion zone at the lower layer decreased from 132.7 to 106.84 mm and permeability improved significantly.展开更多
Atrium spaces,common in modern construction,provide significant fire safety challenges due to their large vertical openings,which facilitate rapid smoke spread and reduce sprinkler effectiveness.Traditional smoke mana...Atrium spaces,common in modern construction,provide significant fire safety challenges due to their large vertical openings,which facilitate rapid smoke spread and reduce sprinkler effectiveness.Traditional smoke management systems primarily rely on make-up air to replace the air expelled through vents.Inadequate calibration,particularly with air velocity,can worsen fire conditions by enhancing oxygen supply,increasing soot production,and reducing visibility,so endangering safe evacuation.This study investigates the impact of make-up air velocity on smoke behaviour in atrium environments through 24 simulations performed using the FireDynamics Simulator(FDS).Scenarios include various fire intensities(1,3,5 MW)and make-up air velocities(1–3.5 m/s),with fire sources located at the centre,northeast,and southwest corners.The simulation model was validated using updated full-scale fire test data with polystyrene fuel,leading to heightened soot density and reduced smoke clear height.This Research design diverges from other studies that predominantly utilized propane pool fires and concentrated on axisymmetric(Fire at the center of the atrum),Northeast and Southeast corners of the atrium scenarios by using polystyrene-a widely accessible construction material and examining several asymetric fire sites,so providing a more authentic depiction of atrium fire settings.Research reveals that increased air velocities,especially when directed at the fire,result in greater soot density and reduced smoke clearance due to intensified combustion.The northeastern region consistently displayed high temperature readings,highlighting the importance of fire source positioning in smoke behaviour.The study recommends limiting make-up air velocity to 1 m/s to avert turbulence and guarantee safety.This research provides critical insights for fire safety design and aligns with the United Nations Sustainable Development Goals,namely SDG 9 and SDG 11,by promoting safer and more resilient construction practices in urban environments.展开更多
The accurate assessment of cardiac motion is crucial for diagnosing and monitoring cardiovascular diseases.In this context,digital volume correlation(DVC)has emerged as a promising technique for tracking cardiac motio...The accurate assessment of cardiac motion is crucial for diagnosing and monitoring cardiovascular diseases.In this context,digital volume correlation(DVC)has emerged as a promising technique for tracking cardiac motion from cardiac computed tomography angiographic(CTA)images.This paper presents a comprehensive performance evaluation of the DVC method,specifically focusing on tracking the motion of the left atrium using cardiac CTA data.The study employed a comparative experimental approach while simultaneously optimizing the existing DVC algorithm.Multiple sets of controlled experiments were designed to conduct quantitative analyses on the parameters“radius”and“step”.The results revealed that the optimized DVC algorithm enhanced tracking accuracy within a reasonable computational time.These findings contributed to the understanding of the efficacy and limitations of the DVC algorithm in analyzing heart deformation.展开更多
The effects of low frequency electromagnetic field on the macro-physical fields in the semi-continuous casting process of aluminum alloys and the microstructure and crack in the billets were studied and analyzed by th...The effects of low frequency electromagnetic field on the macro-physical fields in the semi-continuous casting process of aluminum alloys and the microstructure and crack in the billets were studied and analyzed by the numerical and experimental methods.Comparison of the results for the macro-physical fields in the low frequency electromagnetic casting（LFEC） process with the conventional DC casting process indicates the following characters due to the application of electromagnetic field：an entirely changed direction and remarkably increased velocity of melt flow;a uniform distribution and a decreased gradient of temperature;elevated isothermal lines;a reduced sump depth;decreased stress and plastic deformation.Further,the microstructure of the billets is refined remarkably and the crack in the billets is eliminated in LFEC process because of modification of the macro-physical fields induced by the application of low frequency electromagnetic field.展开更多
[Objective] This study was conducted to construct a super-high yield population of Japnica rice in cold regions of North China and to explore its characteristics. [Method] The super rice variety Longjing 21 was select...[Objective] This study was conducted to construct a super-high yield population of Japnica rice in cold regions of North China and to explore its characteristics. [Method] The super rice variety Longjing 21 was selected as the experimental material. Different row spacing（two levels）, plant spacing（three levels） and seedling number per hill（three levels） were designed in field trials. Then, the growth stages,dry matter accumulation, leaf area, yield and yield components of these different treatments were measured. [Result] Rice yield had significantly negative correlation with plant spacing and row spacing, but no significant correlation with seedling number per hill. Rice yield was mainly affected by plant spacing, and less affected by seedling number per hill. The best recommended specifications for plant spacing of super rice variety Longjing 21 were 24 cm for row spacing, 12 cm for plant spacing and five seedlings per hill, and the expected yield was 10 473.0 kg/hm^2.The increased number of total spikelets（4.5×108hm2or more） in populations was the major reason for high yield. Super-high yield populations had fewer tillers at the early growth stage and achieved the expected number of productive tillers at critical leaf-age（June 25）, and tiller number peaked at jointing stage（July 6） and was about 1.2 times of the expected number. The percentage of productive tillers in total tillers of super-high yield population was more than 85% at heading stage. At middle growth stage（from jointing to heading stage）, the dry matter accumulation, leaf area index（LAI） at heading stage, effective leaf area, spikelet number of population,spikelet number per leaf area unit（cm2）, and culm-sheath weight per stem of super-high yield population were significantly higher than those of other populations.At late growth stage（from heading to maturity stage）, the leaf area decreasing rate of super-high yield population was significantly smaller than that of other populations. At late growth stage（from heading to maturity stage）, the leaf area decreasing rate, crop growth rate, net assimilation rate, biomass accumulation, number of filled grains per leaf area unit（cm^2） and grain weight per leaf area unit（cm^2） of high-yield population were significantly higher than those of other populations. Output and translocation of dry matter（weight per stem and sheath and total filling rate at maturity） from heading to milky stage of super-high yield population were significantly higher than those of other populations. [Conclusion] The characteristics of superhigh yield rice in cold region of North China are enriching the amount of actual filling of sink through improving photosynthetic efficiency from heading to maturity stage on the basis of enough panicle numbers.展开更多
Since the research on verification to passive design strategies in sustainable building is at the initial stage,and its test method and verification conclusion are not scientific enough to validate,this paper proposes...Since the research on verification to passive design strategies in sustainable building is at the initial stage,and its test method and verification conclusion are not scientific enough to validate,this paper proposes the necessity of building physical environmental monitoring to quantitative optimization of passive strategies efficiency from the perspective of architecture design and building environment. Adopting comparative research method,this research chooses six types of atrium space in cold climate in China as a prototype,focusing on building physical environmental performance difference in and between atrium and building main space. Spatial parameters of the atrium space will be divided into four factors: spatial geometry,interfacial properties,internal and external related categories. With subdividing these four factors into sub-factors,this paper makes crosscomparison among the sub-factors to clarify passive strategies effectiveness in atrium. Data comparison analysis shows that Winter atrium passive strategy in cold regions from traditional view is not obvious in practical application,and test data need to be stratified refined in atrium design in case of optimizing passive strategy from building prototype perspective.展开更多
With better understanding of the quality and physico-mechanical properties of rocks of dam foundation,and the physico-mechanical properties and structure design of arch dam in association with the foundation excavatio...With better understanding of the quality and physico-mechanical properties of rocks of dam foundation,and the physico-mechanical properties and structure design of arch dam in association with the foundation excavation of Xiluodu arch dam,the excavation optimization design was proposed for the foundation surface on the basis of feasibility study.Common analysis and numerical analysis results demonstrated the feasibility of using the weakly weathered rocks III1and III2as the foundation surface of super-high arch dam.In view of changes in the geological conditions at the dam foundation along the riverbed direction,the design of extending foundation surface excavation area and using consolidating grouting and optimizing structure of dam bottom was introduced,allowing for harmonization of the arch dam and foundation.Three-dimensional(3D)geomechanics model test and fi nite element analysis results indicated that the dam body and foundation have good overload stability and high bearing capacity.The monitoring data showed that the behaviors of dam and foundation correspond with the designed patterns in the construction period and the initial operation period.展开更多
Based on the thermal and velocity layer's theory,the experimental setup was established on large space atrium under nozzle outlet. A series of winter experiments were accomplished and the following conclusions cou...Based on the thermal and velocity layer's theory,the experimental setup was established on large space atrium under nozzle outlet. A series of winter experiments were accomplished and the following conclusions could be drawn. At the sunny day of winter in Shanghai,the thermal and velocity layer are similar. The height of the both layer is 10-30 mm,and the temperature gratitude is 5-10 ℃ /m. Decreasing the angle of the nozzle outlet can increase the layer height dramatically. The maximum temperature difference of the occupant zone has relation with the angle of the nozzle outlet. The less the angle of the nozzle outlet is set,the greater the temperature difference is. The occupant temperature differences at these angles of the nozzle outlet are 5.1-4.4 ℃. The velocity of the wind is 0.02 and 0.17 m/s and they can accord with design demand. So,it can decrease the temperature gratitude by about 30% and it can save 10%-15% energy consumption.展开更多
The microstructure of Mg-8Zn-1Y alloy solidified under super-high pressure was analyzed through X-ray diffraction（XRD）, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. And, compression...The microstructure of Mg-8Zn-1Y alloy solidified under super-high pressure was analyzed through X-ray diffraction（XRD）, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. And, compression deformation behavior at room-temperature was studied. The results showed that the microstructure of Mg-8Zn-1Y alloy solidified under ambient pressure and super-high pressure was both mainly composed of ■-Mg and quasicrystal I-Mg3Zn6 Y. Solidification under super-high pressure contributed to refining solidified microstructure and changing morphology of the intergranular second phase. The morphology of intergranular second phase（quasicrystal I-Mg3Zn6Y） was transformed from continuous network（ambient pressure） to long island（high pressure） and finally to granular（super-high pressure） with the increase in pressure. The compressive strength, yield strength and rupture strain of the samples solidified under ambient pressure were significantly improved from 262.6 MPa, 244.4 MPa and 13.3% to 437.3 MPa, 368.9 MPa and 24.7% under the pressure of 6 GPa, respectively. Under ambient pressure, cleavage plane on compressive fracture was large and smooth. When it was solidified under the pressure ranging from 4 to 6 GPa, cleavage plane on compressive fracture was small and coarse. In addition, dimple, tear ridge and lobate patterns existed.展开更多
As a transition space,atrium not only organizes traffic,makes the flow line flexible,but also modulates the indoor micro-climate. Because of its good sense of space and lighting performance,designers generally set rea...As a transition space,atrium not only organizes traffic,makes the flow line flexible,but also modulates the indoor micro-climate. Because of its good sense of space and lighting performance,designers generally set reading space around the atrium. But nowadays,people are more concerned with the external form of the architecture,rather than the thermal comfort conditions of the atrium reading space. This article chooses the universities' library atrium space of Harbin in typical city in cold regions as the carrier of research,testes the thermal environment of atrium reading space, analyzes the user 's subjective feelings of the thermal environment and establishes climate adaptation model applied to library buildings. This paper aims to study on Winter thermal comfort of universities' library atrium reading space in cold area. Bases on thermal comfort adaptive model,it establishes a reasonable heating methods and design temperature index of indoor thermal environment. Optimum comfort is obtained while achieving building energy efficiency and providing viewers a comfortable reading space.展开更多
Super-high bed sintering process is an important development direction of iron ore sintering for its lower emission and higher yield.However,there is a lack of deep understanding of the uneven quality of super-high be...Super-high bed sintering process is an important development direction of iron ore sintering for its lower emission and higher yield.However,there is a lack of deep understanding of the uneven quality of super-high bed sintering products,and the deterioration of reduction disintegration performance,the thickening of hearth layer and the reduction in energy-saving effect are perplexing enterprises and researchers.To ascertain the problems of super-high bed sintering,ten sintering machines with the areas of 265,280,360,550 and 660 m^(2)and bed depth above 900 mm were sampled and analyzed.The results showed that problems were mainly shown in the unevenness of chemical composition,macrostructure,mechanical strength and metallurgical performance.The chemical composition exhibits severe segregation in both horizontal and vertical directions,with basicity segregation reaching as high as 0.81.The uneven macrostructure of sinter is reflected in a 10%difference in porosity and mechanical strength increase in 16%–19%along the vertical direction.The reducibility and reduction disintegration performance gradually deteriorate along the bed depth,with a difference of 10.5%in reducibility and 7.3%in RDI−0.5 mm(reduction disintegration index of sinter with size smaller than 0.5 mm).展开更多
CO2-shielded welding experiments of newly developed, 780 MPa super-high strength heavy-duty truck crossbeam steel were conducted, and the microstructure, microhardness, mechanical properties, and impact tough- hess of...CO2-shielded welding experiments of newly developed, 780 MPa super-high strength heavy-duty truck crossbeam steel were conducted, and the microstructure, microhardness, mechanical properties, and impact tough- hess of the welded joint were studied. The evolution of the microstructure of the welded joint occurred as follows.. welding seam （acicular ferrite＋proeutectoid ferrite）→fusion zone （granular bainite-long strip M/A island）→coarse grain zone （granular bainite-long strip or short bar M/A island）→fine grain zone （ferrite＋ pearlite＋ blocky M/A is- land）→mixed grained zone （ferrite＋granular bainite＋blocky M/A island）→base metal （proeutectoid ferrite＋gran- ular bainite-hlocky or granular M/A island）. Increasing the density of the grain boundaries can effectively improve the impact toughness, and the blocky M/A island hindered crack propagation more effectively than the long strip M/A island. The new hot-rolled 780 MPa super-high strength steel had excellent weldability. The welding technology was applied under the following conditions： welding voltage was 20 to 21 V, welding current was 200 to 210 A, and the gas flow rate was 25 L/rain.展开更多
BACKGROUND MicroRNA-21(miR-21)is related to hypertension and cardiac remodelling.Left atrium(LA)dilation is highly sensitive to small haemodynamic changes in the left ventricle(LV)that are induced by hypertension.This...BACKGROUND MicroRNA-21(miR-21)is related to hypertension and cardiac remodelling.Left atrium(LA)dilation is highly sensitive to small haemodynamic changes in the left ventricle(LV)that are induced by hypertension.This study aimed to elucidate the relationship between miR-21 expression and LA dilation in elderly patients with essential hypertension(EH).METHODS In this cross-sectional study,one hundred elderly patients with EH were recruited for the study.According to their left atrium diameters(LADs),the patients were divided into the LA dilation group[42 patients(42%)]and the no-LA dilation group[58 patients(58%)].The serum levels of miR-21 and chemical biomarkers used in the clinic,such as creatinine,blood urea nitrogen,uric acid,fasting blood glucose,total cholesterol(TC),triglyceride(TG),high-density lipoprotein cholesterol(HDLC),low-density lipoprotein cholesterol(LDL-C),very-low-density lipoprotein cholesterol,Lp(a),apolipoprotein A1(apoA1),and apolipoprotein B,were measured.All the patients underwent echocardiographic examination,and the LAD,interventricular septum(IVS),right atrium diameter(RAD),right ventricle diameter(RVD),left ventricular end-systolic diameter(LVESD),left ventricular end-systolic diameter(LVEDD)and left ventricular ejection fraction(LVEF)were measured.RESULTS The levels of miR-21[8.02(5.21,14.39)vs.6.05(3.81,8.95),P=0.011]and LVEF(67.02±3.82 vs.64.14±4.43,P=0.001)were higher in the LA dilation group.The levels of creatinine[70.40(64.45,80.15)vs.63.9(60.1,73.43)],P=0.020]were higher in the no-LA dilation group.The levels of HDLC(r=-0.209,P=0.037),apoA1(r=-0.269,P=0.007)and RAD(r=0.203,P=0.043)were significantly correlated with miR-21 expression.The LAD was significantly correlated with the RAD(r=0.287,P=0.004),RVD(r=0.450,P<0.001),LVEDD(r=0.248,P=0.013)and LVEF(r=0.232,P=0.020).Multivariate logistic regression revealed that miR-21 significantly influenced LA dilation in elderly patients with EH(P<0.05).CONCLUSIONS Circulating serum levels of miR-21 are increased in elderly patients with EH with LA dilation.miR-21 levels are significantly correlated with LA dilation in elderly patients with EH,and miR-21 may be a factor related to the clinical pathophysiological occurrence of and treatment for the progression of hypertension-related early heart damage in EH patients.展开更多
Infective endocarditis(IE) remains a serious disease. Aorta-to-right atrium fistula is a rare but very serious complication of IE and predicts a higher mortality. This report describes a 50-year-old man with endocardi...Infective endocarditis(IE) remains a serious disease. Aorta-to-right atrium fistula is a rare but very serious complication of IE and predicts a higher mortality. This report describes a 50-year-old man with endocarditis,vegetation,perforation of noncoronary sinus,and formation of two aorta-to-right atrium fistulas with native valves detected by transthoracic echocardiography. This disease is lethal despite developments in cardiac imaging and antibacterial therapy. Early diagnosis,aggressive antibacterial therapy,and surgical treatment may improve the prognosis.展开更多
Horizontal segregation has been a constraint to the development and application of super-high bed sintering.To eliminate the horizontal segregation of super-high bed sintering,several typical sintering machines were s...Horizontal segregation has been a constraint to the development and application of super-high bed sintering.To eliminate the horizontal segregation of super-high bed sintering,several typical sintering machines were sampled and analyzed,and theoretical calculation was made to compare the bed depth and their differences in different areas within the mixture bin.Then,solutions were proposed and applied to a 265 m^(2) sintering machine.The results showed that the horizontal seg-regation of the 265 m^(2) sintering machine was dominated by particles larger than 8 mm with horizontal segregation degree of 0.48,while 360 and 550 m^(2) sintering machines were affected by 5-8 mm and 1-3 mm particles with horizontal segregation degree of 0.27 and 0.31,respectively.Causes analysis indicated the different segregation distribution results from the matching of the bed depth of each area within the mixture bin.Finally,the horizontal segregation degree not larger than 0.06 was achieved by optimizing the time parameters and the division of three zones on the 265 m^(2) sintering machine.展开更多
The inhomogeneous sinter properties in super-high bed sintering have been reported in our previous research.To inves-tigate the reasons for the inhomogeneous phenomena,detailed sampling and analysis of mixed material ...The inhomogeneous sinter properties in super-high bed sintering have been reported in our previous research.To inves-tigate the reasons for the inhomogeneous phenomena,detailed sampling and analysis of mixed material bed and sintered bed in super-high bed sintering plant were executed.The results indicated that the higher porosity and thinner dendrite of silico-ferrite of calcium and aluminum in the upper layer as well as dense structure and higher secondary hematite content in the lower layer led to the heterogeneities of mechanical strength and reduction properties exceeding 20%and 10%,respectively.From the bed top downward,the basicity of mixed material decreased from 2.13 to 1.68 because the average particle size increased from 2.65 to 4.56 mm.Fluxes and fuels gathered in finer particles(-3 mm)of mixed material,and the-3 mm particles of mixed material generated more liquid phase than+3 mm ones.The heat input of super-high sintering bed was inhomogeneous due to the heat accumulation effect and unreasonable fuel distribution.The inhomo-geneous sintering heat condition in sintering bed resulted in the different quantities and properties of liquid phase.The inhomogeneous quantities and properties of liquid phase that were influenced by inhomogeneous distribution of chemical composition,particle size,and heat input led to inhomogeneous mineralizing results.Homogeneous mineralizing condition is the key for homogeneous super-high bed sintering.展开更多
Usually, cardiac calcifications are observed in aortic and mitral valves, atrio-ventricular plane, mitral annulus, coronary arteries, pericaridium(usually causing constrictive pericarditis) and cardiac masses. Calcifi...Usually, cardiac calcifications are observed in aortic and mitral valves, atrio-ventricular plane, mitral annulus, coronary arteries, pericaridium(usually causing constrictive pericarditis) and cardiac masses. Calcifications of atrial walls are unusual findings that can be identified only using imaging with high spatial resolution, such as cardiac magnetic resonance and computed tomography. We report a case of a 43-year-old patient with no history of heart disease that underwent cardiac evaluation for mild dyspnoea. The echocardiogram showed a calcific aortic valve and a hyper-echogenic lesion located in atrio-ventricular plane. The patient was submitted to cardiac magnetic resonance and to computed tomography imaging to better characterize the localization of mass. The clinical features and location of calcified lesion suggest an infective aetiology causing an endocarditis involving the aortic valve, atrioventricular plane and left atrium. Although we haven't data to support a definite and clear diagnosis, the clinical features and location of the calcified lesion suggest an infective aetiology causing an endocarditis involving the aortic valve, atrio-ventricular plane and left atrium. The patient was followed for 12 mo both clinically and by electrocardiogram and echocardiography without worsening of clinical, electrocardiographic and echocardiographic data. Cardiac magnetic resonance imaging and computed tomography are ideal methods for identifying and following over time patients with calcific degeneration in the heart.展开更多
Super-high collapse resistant casings were developed by using Ti, Nb and V microalloyed CrMo steel and cross rolling techniques. A transmission electron microscope（TEM） and X-ray diffractometer were used to observe ...Super-high collapse resistant casings were developed by using Ti, Nb and V microalloyed CrMo steel and cross rolling techniques. A transmission electron microscope（TEM） and X-ray diffractometer were used to observe the characteristics of the microstructure. It was found that the （ 111 ） texture and the nano-scale precipitates distribute in a way that is beneficial to the collapse resistance, and the collapse strength of the prepared casing had a measurement, which was approximately 60% higher than the API standard value. A design concept to attain super-high collapse resistance is proposed based on the texture design and microstructure control.展开更多
Super-high pressure(SHP)technique plays an increasing role in the fields of materials science and engineering.Herein,the Mg_(97)Zn_(1)Y_(2) alloy was heat-treated under SHP(6 GPa)by cubic-anvil large-volume press with...Super-high pressure(SHP)technique plays an increasing role in the fields of materials science and engineering.Herein,the Mg_(97)Zn_(1)Y_(2) alloy was heat-treated under SHP(6 GPa)by cubic-anvil large-volume press with six rams for 2 h in the temperature range of 500–1200℃.The microstructure and mechanical properties were investigated.The results indicated that the as-cast sample consists of α-Mg equiaxed dendrites and continuous lamellar long period stacking ordered(LPSO)phase in grain boundaries.After the SHP treatment,the LPSO phase is gradually replaced by eutectic phase(Mg,Zn)_(3)Y with increasing temperature.The microhardness and strength of sample prepared at 1100℃ under SHP treatment are significantly improved compared with the as-cast one at room temperature.The improved mechanical behaviors are mainly attributed to LPSO phase kink-banding strengthening at low temperature and the precipitation strengthening of a large amount of fine(Mg,Zn)_(3)Y particles at high temperature after SHP treatment.It reveals the SHP is an effective approach to prepare high performance Mg alloys.展开更多
基金supported by the Basic Science Center Project for the National Natural Science Foundation of China(No.72088101)the S&T Program of Hebei(No.23564101D).
文摘As the bed depth increases,sintering yield increases,but the productivity decreases.To reveal the reasons for the decrease in productivity and explore targeted solutions,the bed resistance of mixtures,wet zone,and combustion zone was analyzed in the laboratory.The results showed that the decreased porosity of mixture resulted in the increased bed resistance by 160.56%when the bed depth increased from 600 to 1000 mm.After improving porosity of 1%by adding loosening bars with optimized size and distribution,the bed resistance decreased,and the productivity increased by 5%.The increase in bed depth increased the thickness of the wet zone from 120 to 680 mm and the resistance from 1.56 to 8.83 kPa.By using a three-stage intensive mixer and pre-adding water for granulation,the moisture of mixture was reduced by 0.6%,and the sintering productivity increased by 4%.Besides,the high bed resistance is mainly caused by the increase in the thickness of the combustion zone from 31.9 to 132.7 mm,and the bed resistance increased from 0.70 to 5.62 kPa.The bed resistance of the combustion zone at 900 mm was increased by 90.51%compared to 700 mm.After optimization of the distribution of coke breeze,the thickness of combustion zone at the lower layer decreased from 132.7 to 106.84 mm and permeability improved significantly.
文摘Atrium spaces,common in modern construction,provide significant fire safety challenges due to their large vertical openings,which facilitate rapid smoke spread and reduce sprinkler effectiveness.Traditional smoke management systems primarily rely on make-up air to replace the air expelled through vents.Inadequate calibration,particularly with air velocity,can worsen fire conditions by enhancing oxygen supply,increasing soot production,and reducing visibility,so endangering safe evacuation.This study investigates the impact of make-up air velocity on smoke behaviour in atrium environments through 24 simulations performed using the FireDynamics Simulator(FDS).Scenarios include various fire intensities(1,3,5 MW)and make-up air velocities(1–3.5 m/s),with fire sources located at the centre,northeast,and southwest corners.The simulation model was validated using updated full-scale fire test data with polystyrene fuel,leading to heightened soot density and reduced smoke clear height.This Research design diverges from other studies that predominantly utilized propane pool fires and concentrated on axisymmetric(Fire at the center of the atrum),Northeast and Southeast corners of the atrium scenarios by using polystyrene-a widely accessible construction material and examining several asymetric fire sites,so providing a more authentic depiction of atrium fire settings.Research reveals that increased air velocities,especially when directed at the fire,result in greater soot density and reduced smoke clearance due to intensified combustion.The northeastern region consistently displayed high temperature readings,highlighting the importance of fire source positioning in smoke behaviour.The study recommends limiting make-up air velocity to 1 m/s to avert turbulence and guarantee safety.This research provides critical insights for fire safety design and aligns with the United Nations Sustainable Development Goals,namely SDG 9 and SDG 11,by promoting safer and more resilient construction practices in urban environments.
基金supported by the Australian Research Council(ARC)(Grant No.DP200103492)the National Natural Science Foundation of China(Grant Nos.12172089,12372307,and 61821002)+2 种基金Medical Research Future Fund(Grant Nos.2016165 and 2023977)the CBT Early Career Researcher Grant funded and the Roland Bishop Biomedical Engineering Research Award by Queensland University of Technologythe Springboard Funding and the Global Collaboration Funding by London South Bank University.Computational resources and services used in this work were provided by the High-Performance Computing and Research Support Group,Queensland University of Technology,Brisbane,Australia.
文摘The accurate assessment of cardiac motion is crucial for diagnosing and monitoring cardiovascular diseases.In this context,digital volume correlation(DVC)has emerged as a promising technique for tracking cardiac motion from cardiac computed tomography angiographic(CTA)images.This paper presents a comprehensive performance evaluation of the DVC method,specifically focusing on tracking the motion of the left atrium using cardiac CTA data.The study employed a comparative experimental approach while simultaneously optimizing the existing DVC algorithm.Multiple sets of controlled experiments were designed to conduct quantitative analyses on the parameters“radius”and“step”.The results revealed that the optimized DVC algorithm enhanced tracking accuracy within a reasonable computational time.These findings contributed to the understanding of the efficacy and limitations of the DVC algorithm in analyzing heart deformation.
基金Project(2005CB623707)supported by National Basic Research Project of China
文摘The effects of low frequency electromagnetic field on the macro-physical fields in the semi-continuous casting process of aluminum alloys and the microstructure and crack in the billets were studied and analyzed by the numerical and experimental methods.Comparison of the results for the macro-physical fields in the low frequency electromagnetic casting（LFEC） process with the conventional DC casting process indicates the following characters due to the application of electromagnetic field：an entirely changed direction and remarkably increased velocity of melt flow;a uniform distribution and a decreased gradient of temperature;elevated isothermal lines;a reduced sump depth;decreased stress and plastic deformation.Further,the microstructure of the billets is refined remarkably and the crack in the billets is eliminated in LFEC process because of modification of the macro-physical fields induced by the application of low frequency electromagnetic field.
基金Supported by National Key Technology Research and Development Program of China(2011BAD16B11-02YJ01,2012BAD04B01-02)Key Science and Technology Program of Heilongjiang Province+2 种基金China(GA13B101)Heilongjiang Postdoctoral Sustentation Fund(LBH-Z10038)the Funds of Heilongjiang Academy of Agricultural Sciences for Distinguished Young Scholars(2014)~~
文摘[Objective] This study was conducted to construct a super-high yield population of Japnica rice in cold regions of North China and to explore its characteristics. [Method] The super rice variety Longjing 21 was selected as the experimental material. Different row spacing（two levels）, plant spacing（three levels） and seedling number per hill（three levels） were designed in field trials. Then, the growth stages,dry matter accumulation, leaf area, yield and yield components of these different treatments were measured. [Result] Rice yield had significantly negative correlation with plant spacing and row spacing, but no significant correlation with seedling number per hill. Rice yield was mainly affected by plant spacing, and less affected by seedling number per hill. The best recommended specifications for plant spacing of super rice variety Longjing 21 were 24 cm for row spacing, 12 cm for plant spacing and five seedlings per hill, and the expected yield was 10 473.0 kg/hm^2.The increased number of total spikelets（4.5×108hm2or more） in populations was the major reason for high yield. Super-high yield populations had fewer tillers at the early growth stage and achieved the expected number of productive tillers at critical leaf-age（June 25）, and tiller number peaked at jointing stage（July 6） and was about 1.2 times of the expected number. The percentage of productive tillers in total tillers of super-high yield population was more than 85% at heading stage. At middle growth stage（from jointing to heading stage）, the dry matter accumulation, leaf area index（LAI） at heading stage, effective leaf area, spikelet number of population,spikelet number per leaf area unit（cm2）, and culm-sheath weight per stem of super-high yield population were significantly higher than those of other populations.At late growth stage（from heading to maturity stage）, the leaf area decreasing rate of super-high yield population was significantly smaller than that of other populations. At late growth stage（from heading to maturity stage）, the leaf area decreasing rate, crop growth rate, net assimilation rate, biomass accumulation, number of filled grains per leaf area unit（cm^2） and grain weight per leaf area unit（cm^2） of high-yield population were significantly higher than those of other populations. Output and translocation of dry matter（weight per stem and sheath and total filling rate at maturity） from heading to milky stage of super-high yield population were significantly higher than those of other populations. [Conclusion] The characteristics of superhigh yield rice in cold region of North China are enriching the amount of actual filling of sink through improving photosynthetic efficiency from heading to maturity stage on the basis of enough panicle numbers.
基金Sponsored by the Key Project of National Natural Science Foundation of China (Grant No.51138004)the National Science and Technology Support Program (Grant No.2012BAJ10B02)
文摘Since the research on verification to passive design strategies in sustainable building is at the initial stage,and its test method and verification conclusion are not scientific enough to validate,this paper proposes the necessity of building physical environmental monitoring to quantitative optimization of passive strategies efficiency from the perspective of architecture design and building environment. Adopting comparative research method,this research chooses six types of atrium space in cold climate in China as a prototype,focusing on building physical environmental performance difference in and between atrium and building main space. Spatial parameters of the atrium space will be divided into four factors: spatial geometry,interfacial properties,internal and external related categories. With subdividing these four factors into sub-factors,this paper makes crosscomparison among the sub-factors to clarify passive strategies effectiveness in atrium. Data comparison analysis shows that Winter atrium passive strategy in cold regions from traditional view is not obvious in practical application,and test data need to be stratified refined in atrium design in case of optimizing passive strategy from building prototype perspective.
文摘With better understanding of the quality and physico-mechanical properties of rocks of dam foundation,and the physico-mechanical properties and structure design of arch dam in association with the foundation excavation of Xiluodu arch dam,the excavation optimization design was proposed for the foundation surface on the basis of feasibility study.Common analysis and numerical analysis results demonstrated the feasibility of using the weakly weathered rocks III1and III2as the foundation surface of super-high arch dam.In view of changes in the geological conditions at the dam foundation along the riverbed direction,the design of extending foundation surface excavation area and using consolidating grouting and optimizing structure of dam bottom was introduced,allowing for harmonization of the arch dam and foundation.Three-dimensional(3D)geomechanics model test and fi nite element analysis results indicated that the dam body and foundation have good overload stability and high bearing capacity.The monitoring data showed that the behaviors of dam and foundation correspond with the designed patterns in the construction period and the initial operation period.
基金Project(09YZ229) supported by Innovation Program of Shanghai Municipal Education Commission, ChinaProject(J50502) supported by Leading Academic Discipline of Shanghai Municipal Education Commission,China+2 种基金Project(50478113) supported by the National Natural Science Foundation of ChinaProject(2006BAJ02A05) supported by the National Key Technology R&D Program,ChinaProject(08DZ1203600) supported by the Shanghai Municipal Sciences and Technology Committee,China
文摘Based on the thermal and velocity layer's theory,the experimental setup was established on large space atrium under nozzle outlet. A series of winter experiments were accomplished and the following conclusions could be drawn. At the sunny day of winter in Shanghai,the thermal and velocity layer are similar. The height of the both layer is 10-30 mm,and the temperature gratitude is 5-10 ℃ /m. Decreasing the angle of the nozzle outlet can increase the layer height dramatically. The maximum temperature difference of the occupant zone has relation with the angle of the nozzle outlet. The less the angle of the nozzle outlet is set,the greater the temperature difference is. The occupant temperature differences at these angles of the nozzle outlet are 5.1-4.4 ℃. The velocity of the wind is 0.02 and 0.17 m/s and they can accord with design demand. So,it can decrease the temperature gratitude by about 30% and it can save 10%-15% energy consumption.
基金Project supported by National Natural Science Foundation of China(51475486)Natural Science Foundation of Hebei Province(E2013501096)
文摘The microstructure of Mg-8Zn-1Y alloy solidified under super-high pressure was analyzed through X-ray diffraction（XRD）, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. And, compression deformation behavior at room-temperature was studied. The results showed that the microstructure of Mg-8Zn-1Y alloy solidified under ambient pressure and super-high pressure was both mainly composed of ■-Mg and quasicrystal I-Mg3Zn6 Y. Solidification under super-high pressure contributed to refining solidified microstructure and changing morphology of the intergranular second phase. The morphology of intergranular second phase（quasicrystal I-Mg3Zn6Y） was transformed from continuous network（ambient pressure） to long island（high pressure） and finally to granular（super-high pressure） with the increase in pressure. The compressive strength, yield strength and rupture strain of the samples solidified under ambient pressure were significantly improved from 262.6 MPa, 244.4 MPa and 13.3% to 437.3 MPa, 368.9 MPa and 24.7% under the pressure of 6 GPa, respectively. Under ambient pressure, cleavage plane on compressive fracture was large and smooth. When it was solidified under the pressure ranging from 4 to 6 GPa, cleavage plane on compressive fracture was small and coarse. In addition, dimple, tear ridge and lobate patterns existed.
基金Sponsored by the National Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of China(Grant No.2012BAJ06B04-02)
文摘As a transition space,atrium not only organizes traffic,makes the flow line flexible,but also modulates the indoor micro-climate. Because of its good sense of space and lighting performance,designers generally set reading space around the atrium. But nowadays,people are more concerned with the external form of the architecture,rather than the thermal comfort conditions of the atrium reading space. This article chooses the universities' library atrium space of Harbin in typical city in cold regions as the carrier of research,testes the thermal environment of atrium reading space, analyzes the user 's subjective feelings of the thermal environment and establishes climate adaptation model applied to library buildings. This paper aims to study on Winter thermal comfort of universities' library atrium reading space in cold area. Bases on thermal comfort adaptive model,it establishes a reasonable heating methods and design temperature index of indoor thermal environment. Optimum comfort is obtained while achieving building energy efficiency and providing viewers a comfortable reading space.
基金supported by the National Natural Science Foundation of China(Grant No.52274290)the Basic Science Center Project for the National Natural Science Foundation of China(No.72088101).
文摘Super-high bed sintering process is an important development direction of iron ore sintering for its lower emission and higher yield.However,there is a lack of deep understanding of the uneven quality of super-high bed sintering products,and the deterioration of reduction disintegration performance,the thickening of hearth layer and the reduction in energy-saving effect are perplexing enterprises and researchers.To ascertain the problems of super-high bed sintering,ten sintering machines with the areas of 265,280,360,550 and 660 m^(2)and bed depth above 900 mm were sampled and analyzed.The results showed that problems were mainly shown in the unevenness of chemical composition,macrostructure,mechanical strength and metallurgical performance.The chemical composition exhibits severe segregation in both horizontal and vertical directions,with basicity segregation reaching as high as 0.81.The uneven macrostructure of sinter is reflected in a 10%difference in porosity and mechanical strength increase in 16%–19%along the vertical direction.The reducibility and reduction disintegration performance gradually deteriorate along the bed depth,with a difference of 10.5%in reducibility and 7.3%in RDI−0.5 mm(reduction disintegration index of sinter with size smaller than 0.5 mm).
基金Sponsored by National Key Technology Research and Development Program in 11th Five-Year Plan of China (2006BAE03A08)Special Program for Key Research of National Basic Research Program of China (2011CB606306-2)Fundamental Research Funds for Central Universities of China (N090607003)
文摘CO2-shielded welding experiments of newly developed, 780 MPa super-high strength heavy-duty truck crossbeam steel were conducted, and the microstructure, microhardness, mechanical properties, and impact tough- hess of the welded joint were studied. The evolution of the microstructure of the welded joint occurred as follows.. welding seam （acicular ferrite＋proeutectoid ferrite）→fusion zone （granular bainite-long strip M/A island）→coarse grain zone （granular bainite-long strip or short bar M/A island）→fine grain zone （ferrite＋ pearlite＋ blocky M/A is- land）→mixed grained zone （ferrite＋granular bainite＋blocky M/A island）→base metal （proeutectoid ferrite＋gran- ular bainite-hlocky or granular M/A island）. Increasing the density of the grain boundaries can effectively improve the impact toughness, and the blocky M/A island hindered crack propagation more effectively than the long strip M/A island. The new hot-rolled 780 MPa super-high strength steel had excellent weldability. The welding technology was applied under the following conditions： welding voltage was 20 to 21 V, welding current was 200 to 210 A, and the gas flow rate was 25 L/rain.
基金supported by the 2019 Hebei Science and Technology Project (grant number19 277787D)2019 Hebei Innovation Capability Promotion Project (grant number 199776249D)
文摘BACKGROUND MicroRNA-21(miR-21)is related to hypertension and cardiac remodelling.Left atrium(LA)dilation is highly sensitive to small haemodynamic changes in the left ventricle(LV)that are induced by hypertension.This study aimed to elucidate the relationship between miR-21 expression and LA dilation in elderly patients with essential hypertension(EH).METHODS In this cross-sectional study,one hundred elderly patients with EH were recruited for the study.According to their left atrium diameters(LADs),the patients were divided into the LA dilation group[42 patients(42%)]and the no-LA dilation group[58 patients(58%)].The serum levels of miR-21 and chemical biomarkers used in the clinic,such as creatinine,blood urea nitrogen,uric acid,fasting blood glucose,total cholesterol(TC),triglyceride(TG),high-density lipoprotein cholesterol(HDLC),low-density lipoprotein cholesterol(LDL-C),very-low-density lipoprotein cholesterol,Lp(a),apolipoprotein A1(apoA1),and apolipoprotein B,were measured.All the patients underwent echocardiographic examination,and the LAD,interventricular septum(IVS),right atrium diameter(RAD),right ventricle diameter(RVD),left ventricular end-systolic diameter(LVESD),left ventricular end-systolic diameter(LVEDD)and left ventricular ejection fraction(LVEF)were measured.RESULTS The levels of miR-21[8.02(5.21,14.39)vs.6.05(3.81,8.95),P=0.011]and LVEF(67.02±3.82 vs.64.14±4.43,P=0.001)were higher in the LA dilation group.The levels of creatinine[70.40(64.45,80.15)vs.63.9(60.1,73.43)],P=0.020]were higher in the no-LA dilation group.The levels of HDLC(r=-0.209,P=0.037),apoA1(r=-0.269,P=0.007)and RAD(r=0.203,P=0.043)were significantly correlated with miR-21 expression.The LAD was significantly correlated with the RAD(r=0.287,P=0.004),RVD(r=0.450,P<0.001),LVEDD(r=0.248,P=0.013)and LVEF(r=0.232,P=0.020).Multivariate logistic regression revealed that miR-21 significantly influenced LA dilation in elderly patients with EH(P<0.05).CONCLUSIONS Circulating serum levels of miR-21 are increased in elderly patients with EH with LA dilation.miR-21 levels are significantly correlated with LA dilation in elderly patients with EH,and miR-21 may be a factor related to the clinical pathophysiological occurrence of and treatment for the progression of hypertension-related early heart damage in EH patients.
文摘Infective endocarditis(IE) remains a serious disease. Aorta-to-right atrium fistula is a rare but very serious complication of IE and predicts a higher mortality. This report describes a 50-year-old man with endocarditis,vegetation,perforation of noncoronary sinus,and formation of two aorta-to-right atrium fistulas with native valves detected by transthoracic echocardiography. This disease is lethal despite developments in cardiac imaging and antibacterial therapy. Early diagnosis,aggressive antibacterial therapy,and surgical treatment may improve the prognosis.
基金supported by the National Natural Science Foundation of China (Grant No.52274290)the Basic Science Center Project for the National Natural Science Foundation of China (No.72088101).
文摘Horizontal segregation has been a constraint to the development and application of super-high bed sintering.To eliminate the horizontal segregation of super-high bed sintering,several typical sintering machines were sampled and analyzed,and theoretical calculation was made to compare the bed depth and their differences in different areas within the mixture bin.Then,solutions were proposed and applied to a 265 m^(2) sintering machine.The results showed that the horizontal seg-regation of the 265 m^(2) sintering machine was dominated by particles larger than 8 mm with horizontal segregation degree of 0.48,while 360 and 550 m^(2) sintering machines were affected by 5-8 mm and 1-3 mm particles with horizontal segregation degree of 0.27 and 0.31,respectively.Causes analysis indicated the different segregation distribution results from the matching of the bed depth of each area within the mixture bin.Finally,the horizontal segregation degree not larger than 0.06 was achieved by optimizing the time parameters and the division of three zones on the 265 m^(2) sintering machine.
基金This work was supported by the National Natural Science Foundation of China(Grant No.52274290).
文摘The inhomogeneous sinter properties in super-high bed sintering have been reported in our previous research.To inves-tigate the reasons for the inhomogeneous phenomena,detailed sampling and analysis of mixed material bed and sintered bed in super-high bed sintering plant were executed.The results indicated that the higher porosity and thinner dendrite of silico-ferrite of calcium and aluminum in the upper layer as well as dense structure and higher secondary hematite content in the lower layer led to the heterogeneities of mechanical strength and reduction properties exceeding 20%and 10%,respectively.From the bed top downward,the basicity of mixed material decreased from 2.13 to 1.68 because the average particle size increased from 2.65 to 4.56 mm.Fluxes and fuels gathered in finer particles(-3 mm)of mixed material,and the-3 mm particles of mixed material generated more liquid phase than+3 mm ones.The heat input of super-high sintering bed was inhomogeneous due to the heat accumulation effect and unreasonable fuel distribution.The inhomo-geneous sintering heat condition in sintering bed resulted in the different quantities and properties of liquid phase.The inhomogeneous quantities and properties of liquid phase that were influenced by inhomogeneous distribution of chemical composition,particle size,and heat input led to inhomogeneous mineralizing results.Homogeneous mineralizing condition is the key for homogeneous super-high bed sintering.
文摘Usually, cardiac calcifications are observed in aortic and mitral valves, atrio-ventricular plane, mitral annulus, coronary arteries, pericaridium(usually causing constrictive pericarditis) and cardiac masses. Calcifications of atrial walls are unusual findings that can be identified only using imaging with high spatial resolution, such as cardiac magnetic resonance and computed tomography. We report a case of a 43-year-old patient with no history of heart disease that underwent cardiac evaluation for mild dyspnoea. The echocardiogram showed a calcific aortic valve and a hyper-echogenic lesion located in atrio-ventricular plane. The patient was submitted to cardiac magnetic resonance and to computed tomography imaging to better characterize the localization of mass. The clinical features and location of calcified lesion suggest an infective aetiology causing an endocarditis involving the aortic valve, atrioventricular plane and left atrium. Although we haven't data to support a definite and clear diagnosis, the clinical features and location of the calcified lesion suggest an infective aetiology causing an endocarditis involving the aortic valve, atrio-ventricular plane and left atrium. The patient was followed for 12 mo both clinically and by electrocardiogram and echocardiography without worsening of clinical, electrocardiographic and echocardiographic data. Cardiac magnetic resonance imaging and computed tomography are ideal methods for identifying and following over time patients with calcific degeneration in the heart.
文摘Super-high collapse resistant casings were developed by using Ti, Nb and V microalloyed CrMo steel and cross rolling techniques. A transmission electron microscope（TEM） and X-ray diffractometer were used to observe the characteristics of the microstructure. It was found that the （ 111 ） texture and the nano-scale precipitates distribute in a way that is beneficial to the collapse resistance, and the collapse strength of the prepared casing had a measurement, which was approximately 60% higher than the API standard value. A design concept to attain super-high collapse resistance is proposed based on the texture design and microstructure control.
基金NSFC(51101142 and 50821001)New Century Excellent Talents in University of Ministry of Education of China(NCET-12-0690)+1 种基金Hebei province scientific program(13961002D and Y2012019)Hebei Province Technology Foundation for Selected Overseas Chinese and Outstanding Young Scholar.
文摘Super-high pressure(SHP)technique plays an increasing role in the fields of materials science and engineering.Herein,the Mg_(97)Zn_(1)Y_(2) alloy was heat-treated under SHP(6 GPa)by cubic-anvil large-volume press with six rams for 2 h in the temperature range of 500–1200℃.The microstructure and mechanical properties were investigated.The results indicated that the as-cast sample consists of α-Mg equiaxed dendrites and continuous lamellar long period stacking ordered(LPSO)phase in grain boundaries.After the SHP treatment,the LPSO phase is gradually replaced by eutectic phase(Mg,Zn)_(3)Y with increasing temperature.The microhardness and strength of sample prepared at 1100℃ under SHP treatment are significantly improved compared with the as-cast one at room temperature.The improved mechanical behaviors are mainly attributed to LPSO phase kink-banding strengthening at low temperature and the precipitation strengthening of a large amount of fine(Mg,Zn)_(3)Y particles at high temperature after SHP treatment.It reveals the SHP is an effective approach to prepare high performance Mg alloys.
