FeCrAl fiber-reinforced hydroxyapatite（HA） biocomposites（FeCrAl（f）/HA） were fabricated by the hot pressing technique.The metallographic microscopy,X-ray diffractometry,scanning electron microscopy（SEM） and ene...FeCrAl fiber-reinforced hydroxyapatite（HA） biocomposites（FeCrAl（f）/HA） were fabricated by the hot pressing technique.The metallographic microscopy,X-ray diffractometry,scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS） were used to observe and analyze the microstructure and composition of FeCrAl（f）/HA composites,respectively.The mechanical properties of FeCrAl（f）/HA composites were measured by the three-point-bending test.The results show that the composite can be reinforced by FeCrAl fiber and enhanced gradually,and then declined with the increase of the content of FeCrAl fiber（0-11%,volume fraction） in the whole range of experiments.Both the HA matrix and FeCrAl fiber integrate very tightly and bit into each other very deeply and counter-diffusion takes place to some extent at two-phase interface.The optimum parameters of FeCrAl（f）/HA composite are diameter of 22 μm,length of 1-2 mm and of volume faction of about 7% for FeCrAl fibers.展开更多
High temperature compressive deformation behaviors of as-cast Ti-43Al-4Nb-1.4W-0.6B alloy was investigated at temperatures ranging from 1323 K to 1473 K, and strain rates from 0.001 s-1 to 1 s-1. The results indicated...High temperature compressive deformation behaviors of as-cast Ti-43Al-4Nb-1.4W-0.6B alloy was investigated at temperatures ranging from 1323 K to 1473 K, and strain rates from 0.001 s-1 to 1 s-1. The results indicated that the true stress-true strain curves show a dynamic flow softening behavior. The flow curves after the friction and the temperature compensations were employed to develop constitutive equations. The effects of temperature and the strain rate on the deformation behavior were represented by Zener-Holloman exponential equation. The influence of strain was incorporated in the constitutive analysis by considering the effect of the strain on material constants by a five-order polynomial. A revised model was proposed to describe the relationships among the flow stress, strain rate and temperature and the predicted flow stress curves were in good agreement with experimental results. Appropriate deformation processing parameters were suggested based on the processing map which was constructed from friction and temperature corrected flow curves, determined as 1343 K, 0.02 s-1 and were successfully applied in the canned forging of billets to simulate industrial work condition.展开更多
The influences of power spinning process parameters on the mechanical properties of spinning parts were analyzed with an SXD100/3-CNC numerical control power spinning machine.The unidirectional tensile tests were carr...The influences of power spinning process parameters on the mechanical properties of spinning parts were analyzed with an SXD100/3-CNC numerical control power spinning machine.The unidirectional tensile tests were carried out.Based on the experimental data,a ternary quadratic regression equation was established by orthogonal experiment.The Ramberg-Osgood constitutive model of tin-bronze connecting rod bushing was obtained.Referred to the constitutive relation of macroscopic incremental,the incremental elastoplastic constitutive relation of spinning parts was deduced based on the Mises yield criterion and kinematic hardening model.The results can be applied to the elastoplastic analysis in finite element numerical simulation.展开更多
Nursing is known to be a stressful profession that can lead to physical and psychological health issues and behavioural problems.In oncology,workload among nurses is believed to be increasing in conjunction with rapid...Nursing is known to be a stressful profession that can lead to physical and psychological health issues and behavioural problems.In oncology,workload among nurses is believed to be increasing in conjunction with rapidly increasing numbers of patients with cancer and staff shortages worldwide,therefore it is essential to sustain a quality oncology nurse workforce.Numerous studies have presented evidence on job strain,effects of coping strategies,and nurses'work performance within healthcare settings,but few have focused on oncology settings and none of these on nurses working in Saudi Arabia.The purpose of this review was to summarize empirical and theoretical evidence concerning job-related stressors in nurses,particularly oncology nurses,and the interrelationships among job strain,coping strategies,and work performance in this population.Search strategies identified studies published on studies in peer-reviewed journals from 2004 to 2016.Twenty-five nursing studies were found examining the relationships among the concepts of interest.Common job-related stressors among oncology nurses were high job demands,dealing with death/dying,lack of job control,and interpersonal conflicts at work.Job strain was found to be significantly linked to coping strategies,and negatively associated with work performance among nurses in general.There is no existing empirical evidence to support the relationship between coping strategies and work performance among oncology nurses.The present evidence is limited,and a considerable amount of research is required in the future to expand the oncology nursing literature.Research is needed to investigate job-related stressors and their effects on oncology nurses.展开更多
In a karst tunnel, fissures or cracks that are filled with weathered materials are a type of potential water outlet as they are easily triggered and converted into groundwater outlets under the influence of high groun...In a karst tunnel, fissures or cracks that are filled with weathered materials are a type of potential water outlet as they are easily triggered and converted into groundwater outlets under the influence of high groundwater pressure. A terrible water inrush caused by potential water outlets can seriously hinder the project construction. Potential water outlets and water sources that surrounding the tunnel must be detected before water inflow can be treated. This paper provides a successful case of the detection and treatment of water inflow in a karst tunnel and proposes a potential water outlet detection(PWOD) method in which heavy rainfall(>50 mm/d) is considered a trigger for a potential water outlet. The Daba tunnel located in Hunan province, China, has been constructed in a karst stratum where the rock mass has been weathered intensely by the influence of two faults. Heavy rain triggered some potential water outlets, causing a serious water inrush. The PWOD method was applied in this project for the treatment of water inflow, and six potential water outlets in total were identified through three heavy rains. Meanwhile, a geophysical prospecting technique was also used to detect water sources. The connections between water outlets and water sources were identified with a 3-D graphic that included all of them. According to the distribution of water outlets and water sources, the detection area was divided into three sections and separately treated by curtain grouting.展开更多
The present work numerically investigates two-dimensional （2-D） solidification transport phenomena （EM-STP） during continuous casting （CC） process in the absence and the presence of static magnetic fields （SMFs...The present work numerically investigates two-dimensional （2-D） solidification transport phenomena （EM-STP） during continuous casting （CC） process in the absence and the presence of static magnetic fields （SMFs）, based on a unified numerical model. For the purpose of controlling vortexes, the electromagnetic brake （EMBR） effects of various SMFs under the given depth of submerged entry nozzle （SEN） and the same casting velocity V0 are investigated. ANSYS software is used to analyze the SMFs that applied to the EMCC process, and then a data-conversion program based on the principle of linear interpolation proposed previously is used to deal with the issue of data-format-matching between FEM and FVM. The simulation results indicate that, an appropriate SMF can effectively suppress the bulk liquid flow in CC-process of steel plate, and with in- crease of the intensity of applied magnetic fields, the vortexes become weaker and the oscillating amplitude of impinging jet decreases. Based on the knowledge gained from the EMCC-STP analysis and by comparing the re- sults with the applied magnetic fields with those without magnetic fields, it is found that a SMF with 丨 Bmax 丨 = 5.5 × 10 -3 T can meet the need of braking, and consequently improve the quality of casting by reducing the penetration of non-metallic inclusions, as well as avoiding breakout, macro-segregation and crack ultimately.展开更多
基金Project(50774096) supported by the National Natural Science Foundation of ChinaProject(2011QNZT046) supported by the Fundamental Research Funds of the Central South University,ChinaProject supported by the Postdoctoral Science Foundation of Central South University,China
文摘FeCrAl fiber-reinforced hydroxyapatite（HA） biocomposites（FeCrAl（f）/HA） were fabricated by the hot pressing technique.The metallographic microscopy,X-ray diffractometry,scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS） were used to observe and analyze the microstructure and composition of FeCrAl（f）/HA composites,respectively.The mechanical properties of FeCrAl（f）/HA composites were measured by the three-point-bending test.The results show that the composite can be reinforced by FeCrAl fiber and enhanced gradually,and then declined with the increase of the content of FeCrAl fiber（0-11%,volume fraction） in the whole range of experiments.Both the HA matrix and FeCrAl fiber integrate very tightly and bit into each other very deeply and counter-diffusion takes place to some extent at two-phase interface.The optimum parameters of FeCrAl（f）/HA composite are diameter of 22 μm,length of 1-2 mm and of volume faction of about 7% for FeCrAl fibers.
基金Project(2011CB605505)supported by the National Key Fundamental Research Development Project of ChinaProjects(51301204,51174233)supported by the National Natural Science Foundation of ChinaProject(2011JQ002)supported by the Fundamental Research Funds for the Central Universities of China
文摘High temperature compressive deformation behaviors of as-cast Ti-43Al-4Nb-1.4W-0.6B alloy was investigated at temperatures ranging from 1323 K to 1473 K, and strain rates from 0.001 s-1 to 1 s-1. The results indicated that the true stress-true strain curves show a dynamic flow softening behavior. The flow curves after the friction and the temperature compensations were employed to develop constitutive equations. The effects of temperature and the strain rate on the deformation behavior were represented by Zener-Holloman exponential equation. The influence of strain was incorporated in the constitutive analysis by considering the effect of the strain on material constants by a five-order polynomial. A revised model was proposed to describe the relationships among the flow stress, strain rate and temperature and the predicted flow stress curves were in good agreement with experimental results. Appropriate deformation processing parameters were suggested based on the processing map which was constructed from friction and temperature corrected flow curves, determined as 1343 K, 0.02 s-1 and were successfully applied in the canned forging of billets to simulate industrial work condition.
基金Project(2012011023-2)supported by the Natural Science Foundation of Shanxi Province,China
文摘The influences of power spinning process parameters on the mechanical properties of spinning parts were analyzed with an SXD100/3-CNC numerical control power spinning machine.The unidirectional tensile tests were carried out.Based on the experimental data,a ternary quadratic regression equation was established by orthogonal experiment.The Ramberg-Osgood constitutive model of tin-bronze connecting rod bushing was obtained.Referred to the constitutive relation of macroscopic incremental,the incremental elastoplastic constitutive relation of spinning parts was deduced based on the Mises yield criterion and kinematic hardening model.The results can be applied to the elastoplastic analysis in finite element numerical simulation.
文摘Nursing is known to be a stressful profession that can lead to physical and psychological health issues and behavioural problems.In oncology,workload among nurses is believed to be increasing in conjunction with rapidly increasing numbers of patients with cancer and staff shortages worldwide,therefore it is essential to sustain a quality oncology nurse workforce.Numerous studies have presented evidence on job strain,effects of coping strategies,and nurses'work performance within healthcare settings,but few have focused on oncology settings and none of these on nurses working in Saudi Arabia.The purpose of this review was to summarize empirical and theoretical evidence concerning job-related stressors in nurses,particularly oncology nurses,and the interrelationships among job strain,coping strategies,and work performance in this population.Search strategies identified studies published on studies in peer-reviewed journals from 2004 to 2016.Twenty-five nursing studies were found examining the relationships among the concepts of interest.Common job-related stressors among oncology nurses were high job demands,dealing with death/dying,lack of job control,and interpersonal conflicts at work.Job strain was found to be significantly linked to coping strategies,and negatively associated with work performance among nurses in general.There is no existing empirical evidence to support the relationship between coping strategies and work performance among oncology nurses.The present evidence is limited,and a considerable amount of research is required in the future to expand the oncology nursing literature.Research is needed to investigate job-related stressors and their effects on oncology nurses.
基金supported by the National Key Research and Development Project (Grant No.2016YFC0801604)Natural Science Foundation of Shandong Province (Grant No.ZR2017MEE070)
文摘In a karst tunnel, fissures or cracks that are filled with weathered materials are a type of potential water outlet as they are easily triggered and converted into groundwater outlets under the influence of high groundwater pressure. A terrible water inrush caused by potential water outlets can seriously hinder the project construction. Potential water outlets and water sources that surrounding the tunnel must be detected before water inflow can be treated. This paper provides a successful case of the detection and treatment of water inflow in a karst tunnel and proposes a potential water outlet detection(PWOD) method in which heavy rainfall(>50 mm/d) is considered a trigger for a potential water outlet. The Daba tunnel located in Hunan province, China, has been constructed in a karst stratum where the rock mass has been weathered intensely by the influence of two faults. Heavy rain triggered some potential water outlets, causing a serious water inrush. The PWOD method was applied in this project for the treatment of water inflow, and six potential water outlets in total were identified through three heavy rains. Meanwhile, a geophysical prospecting technique was also used to detect water sources. The connections between water outlets and water sources were identified with a 3-D graphic that included all of them. According to the distribution of water outlets and water sources, the detection area was divided into three sections and separately treated by curtain grouting.
基金Sponsored by the National Natural Science Foundation of China (Grants No. 50801019,51071062)the State Key Lab of Advanced Metals Materials(Grant No.2009ZD-06)the National Basic Research Program of China (Grant No. 2011CB605504)
文摘The present work numerically investigates two-dimensional （2-D） solidification transport phenomena （EM-STP） during continuous casting （CC） process in the absence and the presence of static magnetic fields （SMFs）, based on a unified numerical model. For the purpose of controlling vortexes, the electromagnetic brake （EMBR） effects of various SMFs under the given depth of submerged entry nozzle （SEN） and the same casting velocity V0 are investigated. ANSYS software is used to analyze the SMFs that applied to the EMCC process, and then a data-conversion program based on the principle of linear interpolation proposed previously is used to deal with the issue of data-format-matching between FEM and FVM. The simulation results indicate that, an appropriate SMF can effectively suppress the bulk liquid flow in CC-process of steel plate, and with in- crease of the intensity of applied magnetic fields, the vortexes become weaker and the oscillating amplitude of impinging jet decreases. Based on the knowledge gained from the EMCC-STP analysis and by comparing the re- sults with the applied magnetic fields with those without magnetic fields, it is found that a SMF with 丨 Bmax 丨 = 5.5 × 10 -3 T can meet the need of braking, and consequently improve the quality of casting by reducing the penetration of non-metallic inclusions, as well as avoiding breakout, macro-segregation and crack ultimately.
