Thermal conductivity is one of the most significant criterion of three-dimensional carbon fiber-reinforced SiC matrix composites(3D C/SiC).Represent volume element(RVE)models of microscale,void/matrix and mesoscale pr...Thermal conductivity is one of the most significant criterion of three-dimensional carbon fiber-reinforced SiC matrix composites(3D C/SiC).Represent volume element(RVE)models of microscale,void/matrix and mesoscale proposed in this work are used to simulate the thermal conductivity behaviors of the 3D C/SiC composites.An entirely new process is introduced to weave the preform with three-dimensional orthogonal architecture.The 3D steady-state analysis step is created for assessing the thermal conductivity behaviors of the composites by applying periodic temperature boundary conditions.Three RVE models of cuboid,hexagonal and fiber random distribution are respectively developed to comparatively study the influence of fiber package pattern on the thermal conductivities at the microscale.Besides,the effect of void morphology on the thermal conductivity of the matrix is analyzed by the void/matrix models.The prediction results at the mesoscale correspond closely to the experimental values.The effect of the porosities and fiber volume fractions on the thermal conductivities is also taken into consideration.The multi-scale models mentioned in this paper can be used to predict the thermal conductivity behaviors of other composites with complex structures.展开更多
Hydrological models are very useful tools for evaluating water resources, and the hydroclimatic hazards associated with the water cycle. However, their calibration and validation require the use of performance criteri...Hydrological models are very useful tools for evaluating water resources, and the hydroclimatic hazards associated with the water cycle. However, their calibration and validation require the use of performance criteria which choice is not straightforward. This paper aims to evaluate the influence of the performance criteria on water balance components and water extremes using two global rainfall-runoff models (HBV and GR4J) over the Ouémé watershed at the Bonou and Savè outlets. Three (3) Efficacy criteria (Nash, coefficient of determination, and KGE) were considered for calibration and validation. The results show that the Nash criterion provides a good assessment of the simulation of the different parts of the hydrograph. KGE is better for simulating peak flows and water balance elements than other efficiency criteria. This study could serve as a basis for the choice of performance criteria in hydrological modelling.展开更多
Coal has a highly complex chemical structure,similar to polymers,coal is a macromolecular structure composed of a large number of“similar compounds”,which is called the basic structural unit.Understanding coal struc...Coal has a highly complex chemical structure,similar to polymers,coal is a macromolecular structure composed of a large number of“similar compounds”,which is called the basic structural unit.Understanding coal structure is the basis of its transformation and utilization.Shendong(SD)coal was analyzed by FTIR,XRD,XPS,and NMR.The results show that SD coal normalized structure formula is C_(100)H_(68.5)O_(35.7)N_(1.2)S_(0.2)and the average number of aromatic rings is 1.98.-CH_(2)-content accounts for about 82%in aliphatic CeH region,and the ratio of ether bond CeO,aromatic ether C-O and C=O is about 2:1:11 in oxygen-containing functional group region.The d_(002),L_(C),L_(a)and N_(C)of S_(D)coal microcrystalline structure parameters are 0.1832 nm,1.4688 nm,2.0852 nm and 9.017,respectively.Aromatic carbon and aliphatic carbon ratios of SD coal are 55.67%and 29.97%,aromatic cluster size and average methylene chain length are 0.224 and 1.817.Based on these structural parameters,molecular model of SD coal was constructed with^(13)C SSNMR experimental spectra as a reference.The model was constructed with an atom composition of C_(214)H_(214)O_(49)N_(2)S.展开更多
Flow records for stations in the Casamance basin are incomplete. Several gaps were noted over the 1980-2021 study period, making this study tedious. The aim of this study is to assess the potential impact of climate c...Flow records for stations in the Casamance basin are incomplete. Several gaps were noted over the 1980-2021 study period, making this study tedious. The aim of this study is to assess the potential impact of climate change on the flow of the Casamance watershed at Kolda. To this end, hydrological series are simulated and then extended using the GR2M rainfall-runoff model, with a monthly time step. Projected climate data are derived from a multi-model ensemble under scenarios SSP2-4.5 (scenario with additional radiative forcing of 4.5 W/m<sup>2</sup> by 2099) and SSP5-8.5 (scenario with additional radiative forcing of 8.5 W/m<sup>2</sup> by 2099). An analysis of the homogeneity of the rainfall data series from the Kolda station was carried out using KhronoStat software. The Casamance watershed was then delimited using ArcGIS to determine the morphometric parameters of the basin, which will be decisive for the rest of the work. Next, monthly evapotranspiration was calculated using the formula proposed by Oudin et al. This, together with rainfall and runoff, forms the input data for the model. The GR2M model was then calibrated and cross-validated using various simulations to assess its performance and robustness in the Casamance watershed. The version of the model with the calibrated parameters will make it possible to extend Casamance river flows to 2099. This simulation of future flows with GR2M shows a decrease in the flow of the Casamance at Kolda with the two scenarios SSP2-4.5 and SSP5-8.5 during the rainy period, and almost zero flows during the dry season from the period 2040-2059.展开更多
Objective:To construct a scientific and feasible teaching mode based on 5C caring theory and evaluate it,so as to provide a reference basis for future study about nursing humanistic quality education.Methods:Based on ...Objective:To construct a scientific and feasible teaching mode based on 5C caring theory and evaluate it,so as to provide a reference basis for future study about nursing humanistic quality education.Methods:Based on the 5C caring theory,the teaching design and teaching content were revising and implementing in the intervention group.Before and after the implementation of the course,a questionnaire survey was conducted using the Caring Ability Inventory(CAI).The results of the surveys were collected,and the data were statistically analysis using SPSS.Results:After the implementation of the course,the cognitive dimension,patience dimension,and humanistic caring ability scores of the nursing students in the intervention group improved compared with those before the implementation of the course(P<0.05).There were no significant difference in the control group(P>0.05).Conclusion:The humanistic caring teaching model based on 5C caring theory has a positive effect on improving nursing students'humanistic caring ability.In the future nursing teaching,the modules with the characteristics of humanistic caring ability can be increased,and carry out the educational reform throughout the humanistic caring ability.Actively guiding nursing students to establish the awareness of humanistic caring,so as to lay a solid foundation for high-quality clinical nursing work.展开更多
[ Objectlve] Impulsive Logistic Model was used to simulate epidemic process of Gray Leaf Spots caused by C. zeae-maydi. [ Method] The pathogen was inoculated in different maize varieties, and the incidence were observ...[ Objectlve] Impulsive Logistic Model was used to simulate epidemic process of Gray Leaf Spots caused by C. zeae-maydi. [ Method] The pathogen was inoculated in different maize varieties, and the incidence were observed and recorded. Impulsive Logistic Model was used to simulate the development process of the disease, which was compared with actual incidence. [ Result] Artificial inoculation tests showed that impulsive Logistic Model could reflect time dynamic of C. zeae-maydi. Through derivation, exponential growth phase was from maize seedling emergence to eady July in each year, logistic phase was from early July to late August, terminal phase was from eady September to the end of maize growth stage. [ Conclusion] The derivation result from model was consistent with the development biological laws of C. zeae-maydi.展开更多
Aim To define a mixed redundant model(MRM), improving the reliability of C 3I system. Methods The model combined the technology characters of two? unit system with one warm stand by unit and function substitute s...Aim To define a mixed redundant model(MRM), improving the reliability of C 3I system. Methods The model combined the technology characters of two? unit system with one warm stand by unit and function substitute system. The reliability and availability equations of MRM were deduced. Results and Conclusion Compared with several other reliability models, it has obvious effect upon improving the system reliability. The effect? cost rate is very high among these models. The model can be used in reliability design, evaluation and check of C 3I system. Only a little attached cost is needed to improve C 3I system reliability effectively.展开更多
The early precipitation process of Ni(75)Al(14)Mo(11) alloy was simulated by microscopic phase-field model at different temperatures.The microstructure of the alloy,the precipitation time of Llo structure and oc...The early precipitation process of Ni(75)Al(14)Mo(11) alloy was simulated by microscopic phase-field model at different temperatures.The microstructure of the alloy,the precipitation time of Llo structure and occupation probability of the three kinds of atoms were investigated.It is indicated that the non-stoichiometric Ll0(Ⅰ/Ⅱ) phases are found in the precipitation process.With the temperature increasing,the appearance time of Ll0 is brought forward.The Ll0(Ⅱ) structure always precipitates earlier than the Ll0(Ⅰ) structure.Compared with lower temperature,higher temperature brings the formation time of Ll0 phase forward and makes Ll0 phase have a higher order degree.But lower temperature shortens the process time of the Ll0 phase to the Ll2 phase.Al and Mo atoms tend to occupy γ site,Ni atom tends to occupy a and β sites.At the same temperature,Al atom has stronger occupation ability than Mo atom in the same site.Ni,Al and Mo collectively form the composited Ll2 structure.展开更多
Using a modified C D function and stochastic frontier model, the paper analyzed China's cotton yield capacity and found that the yield and technical efficiency of China's cotton planting system can be increas...Using a modified C D function and stochastic frontier model, the paper analyzed China's cotton yield capacity and found that the yield and technical efficiency of China's cotton planting system can be increased by the use of genetically modified (GM) varieties.展开更多
基金Supported by Science Center for Gas Turbine Project of China (Grant No.P2022-B-IV-014-001)Frontier Leading Technology Basic Research Special Project of Jiangsu Province of China (Grant No.BK20212007)the BIT Research and Innovation Promoting Project of China (Grant No.2022YCXZ019)。
文摘Thermal conductivity is one of the most significant criterion of three-dimensional carbon fiber-reinforced SiC matrix composites(3D C/SiC).Represent volume element(RVE)models of microscale,void/matrix and mesoscale proposed in this work are used to simulate the thermal conductivity behaviors of the 3D C/SiC composites.An entirely new process is introduced to weave the preform with three-dimensional orthogonal architecture.The 3D steady-state analysis step is created for assessing the thermal conductivity behaviors of the composites by applying periodic temperature boundary conditions.Three RVE models of cuboid,hexagonal and fiber random distribution are respectively developed to comparatively study the influence of fiber package pattern on the thermal conductivities at the microscale.Besides,the effect of void morphology on the thermal conductivity of the matrix is analyzed by the void/matrix models.The prediction results at the mesoscale correspond closely to the experimental values.The effect of the porosities and fiber volume fractions on the thermal conductivities is also taken into consideration.The multi-scale models mentioned in this paper can be used to predict the thermal conductivity behaviors of other composites with complex structures.
文摘Hydrological models are very useful tools for evaluating water resources, and the hydroclimatic hazards associated with the water cycle. However, their calibration and validation require the use of performance criteria which choice is not straightforward. This paper aims to evaluate the influence of the performance criteria on water balance components and water extremes using two global rainfall-runoff models (HBV and GR4J) over the Ouémé watershed at the Bonou and Savè outlets. Three (3) Efficacy criteria (Nash, coefficient of determination, and KGE) were considered for calibration and validation. The results show that the Nash criterion provides a good assessment of the simulation of the different parts of the hydrograph. KGE is better for simulating peak flows and water balance elements than other efficiency criteria. This study could serve as a basis for the choice of performance criteria in hydrological modelling.
基金financed by the Department of education of Gansu Province:Young Doctor Fund Project(2022QB-029)the Fundamental Research Funds for the Central Universities(31920240125-06,31920240059)+1 种基金the Scientific Research Project of Introducing Talents of Northwest Minzu University(xbmuyjrc202215,xbmuyjrc202216)the National Natural Science Foundation of China(22178289).
文摘Coal has a highly complex chemical structure,similar to polymers,coal is a macromolecular structure composed of a large number of“similar compounds”,which is called the basic structural unit.Understanding coal structure is the basis of its transformation and utilization.Shendong(SD)coal was analyzed by FTIR,XRD,XPS,and NMR.The results show that SD coal normalized structure formula is C_(100)H_(68.5)O_(35.7)N_(1.2)S_(0.2)and the average number of aromatic rings is 1.98.-CH_(2)-content accounts for about 82%in aliphatic CeH region,and the ratio of ether bond CeO,aromatic ether C-O and C=O is about 2:1:11 in oxygen-containing functional group region.The d_(002),L_(C),L_(a)and N_(C)of S_(D)coal microcrystalline structure parameters are 0.1832 nm,1.4688 nm,2.0852 nm and 9.017,respectively.Aromatic carbon and aliphatic carbon ratios of SD coal are 55.67%and 29.97%,aromatic cluster size and average methylene chain length are 0.224 and 1.817.Based on these structural parameters,molecular model of SD coal was constructed with^(13)C SSNMR experimental spectra as a reference.The model was constructed with an atom composition of C_(214)H_(214)O_(49)N_(2)S.
文摘Flow records for stations in the Casamance basin are incomplete. Several gaps were noted over the 1980-2021 study period, making this study tedious. The aim of this study is to assess the potential impact of climate change on the flow of the Casamance watershed at Kolda. To this end, hydrological series are simulated and then extended using the GR2M rainfall-runoff model, with a monthly time step. Projected climate data are derived from a multi-model ensemble under scenarios SSP2-4.5 (scenario with additional radiative forcing of 4.5 W/m<sup>2</sup> by 2099) and SSP5-8.5 (scenario with additional radiative forcing of 8.5 W/m<sup>2</sup> by 2099). An analysis of the homogeneity of the rainfall data series from the Kolda station was carried out using KhronoStat software. The Casamance watershed was then delimited using ArcGIS to determine the morphometric parameters of the basin, which will be decisive for the rest of the work. Next, monthly evapotranspiration was calculated using the formula proposed by Oudin et al. This, together with rainfall and runoff, forms the input data for the model. The GR2M model was then calibrated and cross-validated using various simulations to assess its performance and robustness in the Casamance watershed. The version of the model with the calibrated parameters will make it possible to extend Casamance river flows to 2099. This simulation of future flows with GR2M shows a decrease in the flow of the Casamance at Kolda with the two scenarios SSP2-4.5 and SSP5-8.5 during the rainy period, and almost zero flows during the dry season from the period 2040-2059.
基金supported by the Research Program on Educational Teaching Reform of Tianjin University of Traditional Chinese Medicine(2020JY041)。
文摘Objective:To construct a scientific and feasible teaching mode based on 5C caring theory and evaluate it,so as to provide a reference basis for future study about nursing humanistic quality education.Methods:Based on the 5C caring theory,the teaching design and teaching content were revising and implementing in the intervention group.Before and after the implementation of the course,a questionnaire survey was conducted using the Caring Ability Inventory(CAI).The results of the surveys were collected,and the data were statistically analysis using SPSS.Results:After the implementation of the course,the cognitive dimension,patience dimension,and humanistic caring ability scores of the nursing students in the intervention group improved compared with those before the implementation of the course(P<0.05).There were no significant difference in the control group(P>0.05).Conclusion:The humanistic caring teaching model based on 5C caring theory has a positive effect on improving nursing students'humanistic caring ability.In the future nursing teaching,the modules with the characteristics of humanistic caring ability can be increased,and carry out the educational reform throughout the humanistic caring ability.Actively guiding nursing students to establish the awareness of humanistic caring,so as to lay a solid foundation for high-quality clinical nursing work.
基金Supported by Doctoral Fundation of Liaoning Province(20081064)Liaoning BaiQianWan Talents Program(2009921072)Ministry of Agriculture,National Research Subject(2004BA520A11)~~
文摘[ Objectlve] Impulsive Logistic Model was used to simulate epidemic process of Gray Leaf Spots caused by C. zeae-maydi. [ Method] The pathogen was inoculated in different maize varieties, and the incidence were observed and recorded. Impulsive Logistic Model was used to simulate the development process of the disease, which was compared with actual incidence. [ Result] Artificial inoculation tests showed that impulsive Logistic Model could reflect time dynamic of C. zeae-maydi. Through derivation, exponential growth phase was from maize seedling emergence to eady July in each year, logistic phase was from early July to late August, terminal phase was from eady September to the end of maize growth stage. [ Conclusion] The derivation result from model was consistent with the development biological laws of C. zeae-maydi.
文摘Aim To define a mixed redundant model(MRM), improving the reliability of C 3I system. Methods The model combined the technology characters of two? unit system with one warm stand by unit and function substitute system. The reliability and availability equations of MRM were deduced. Results and Conclusion Compared with several other reliability models, it has obvious effect upon improving the system reliability. The effect? cost rate is very high among these models. The model can be used in reliability design, evaluation and check of C 3I system. Only a little attached cost is needed to improve C 3I system reliability effectively.
基金Project(51275486)supported by the National Natural Science Foundation of China
文摘The early precipitation process of Ni(75)Al(14)Mo(11) alloy was simulated by microscopic phase-field model at different temperatures.The microstructure of the alloy,the precipitation time of Llo structure and occupation probability of the three kinds of atoms were investigated.It is indicated that the non-stoichiometric Ll0(Ⅰ/Ⅱ) phases are found in the precipitation process.With the temperature increasing,the appearance time of Ll0 is brought forward.The Ll0(Ⅱ) structure always precipitates earlier than the Ll0(Ⅰ) structure.Compared with lower temperature,higher temperature brings the formation time of Ll0 phase forward and makes Ll0 phase have a higher order degree.But lower temperature shortens the process time of the Ll0 phase to the Ll2 phase.Al and Mo atoms tend to occupy γ site,Ni atom tends to occupy a and β sites.At the same temperature,Al atom has stronger occupation ability than Mo atom in the same site.Ni,Al and Mo collectively form the composited Ll2 structure.
文摘Using a modified C D function and stochastic frontier model, the paper analyzed China's cotton yield capacity and found that the yield and technical efficiency of China's cotton planting system can be increased by the use of genetically modified (GM) varieties.