Semi-implicit direct kinetics(SIDK)is an innovative method for the temporal discretization of neutronic equations proposed by J.Banfield.The key approximation of the SIDK method is to substitute a timeaveraged quantit...Semi-implicit direct kinetics(SIDK)is an innovative method for the temporal discretization of neutronic equations proposed by J.Banfield.The key approximation of the SIDK method is to substitute a timeaveraged quantity for the fission source term in the delayed neutron differential equations.Hence,these equations are decoupled from prompt neutron equations and an explicit analytical representation of precursor groups is obtained,which leads to a significant reduction in computational cost.As the fission source is not known in a time step,the original study suggested using a constant quantity pertaining to the previous time step for this purpose,and a reduction in the size of the time step was proposed to lessen the imposed errors.However,this remedy notably diminishes the main advantage of the SIDK method.We discerned that if the original method is properly introduced into the algorithm of the point-implicit solver along with some modifications,the mentioned drawbacks will be mitigated adequately.To test this idea,a novel multigroup,multi-dimensional diffusion code using the finitevolume method and a point-implicit solver is developed which works in both transient and steady states.In addition to the SIDK,two other kinetic methods,i.e.,direct kinetics and higher-order backward discretization,are programmed into the diffusion code for comparison with the proposed model.The final code is tested at different conditions of two well-known transient benchmark problems.Results indicate that while the accuracy of the improved SIDK is closely comparable with the best available kinetic methods,it reduces the total time required for computation by up to 24%.展开更多
目的:探讨成人和儿童术前乳酸林格氏液液体动力学的差别。方法:本研究是随机,双盲前瞻性研究。择期盆腔、肛肠或者下肢小手术患者28例,美国麻醉医师协会(ASA)I级,其中儿童14例,成人14例。所有患者给予镇静药后在20 min内恒速输入10 m L...目的:探讨成人和儿童术前乳酸林格氏液液体动力学的差别。方法:本研究是随机,双盲前瞻性研究。择期盆腔、肛肠或者下肢小手术患者28例,美国麻醉医师协会(ASA)I级,其中儿童14例,成人14例。所有患者给予镇静药后在20 min内恒速输入10 m L/kg的乳酸林格氏液体,通过血红蛋白(Hb)稀释-时间曲线和尿量采用Matlab 4.2软件包计算液体动力学参数。结果:一级动力学模型拟合结果显示,与成人相比,在输入林格氏液体后90 min内儿童的血浆稀释程度明显降低(0.16 vs 0.07,P=0.000),儿童将输入液体的43%通过肾脏排出,显著高于成人(18%)(P=0.011)。按公斤体重计算儿童和成人对乳酸林格氏液的血浆清除率分别是2.2 m L·min-1·kg-1和0.5 m L·min-1·kg-1(P=0.016),而肾脏对乳酸林格氏液体的清除率两组分别是0.76 m L·min-1·kg-1和0.10 m L·min-1·kg-1,(P=0.000)。结论:儿童对乳酸林格氏液体血浆和肾脏清除率分别是成人的4倍和7倍,术前给儿童输液,按照体重计算量可以参照成人的剂量。展开更多
Precipitation behavior of the early aging stage and the transformation kinetics were studied by analysing the electrical resistance variation of the solution Cu-Ni-Si alloy in the process of aging. Due to the linear r...Precipitation behavior of the early aging stage and the transformation kinetics were studied by analysing the electrical resistance variation of the solution Cu-Ni-Si alloy in the process of aging. Due to the linear relationship between electrical conductivity and volume fraction of precipitates, the transformation kinetics equation can be educed from the Avrami empirical formula, on the basis of this equation, transformation kinetics curve and "C" curve of the isothermal transformation were established.展开更多
The aging precipitation behavior in solution treated Cu-Ni-Si-Cr alloy has been studied in terms of the analyses of the variations in electrical conductivity. On the basis of the linear relationship between the electr...The aging precipitation behavior in solution treated Cu-Ni-Si-Cr alloy has been studied in terms of the analyses of the variations in electrical conductivity. On the basis of the linear relationship between the electrical conductivity and the volume fraction of the precipitates, the phase transformation kinetics equation was deduced from the Avrami empiricai formula. On the basis of this equation, transformation kinetics curves corresponding to 5% and 50% transformation were established.展开更多
On the basis of phase transformation kinetics, the transformation of γ→α,P,B have been investigated through considering the effect of deformation. The calculation methods of volume fraction have also been given. Co...On the basis of phase transformation kinetics, the transformation of γ→α,P,B have been investigated through considering the effect of deformation. The calculation methods of volume fraction have also been given. Comparing with common method, the simulated results are in more agreement with experiment results.展开更多
In situ observation of the growth process of bainitic plate in βbrass by means of high-temper- ature TEM is conducted.The lengthening and thickening kinetics of bainitic plate is analysed with Trivedi's model and...In situ observation of the growth process of bainitic plate in βbrass by means of high-temper- ature TEM is conducted.The lengthening and thickening kinetics of bainitic plate is analysed with Trivedi's model and Zener-Hillert's model,respectively.It is found that the stacking fault substructure exists just in the growth tip of fresh bainitie plate and so does the shear stress in the matrix around the tip.The measured lengthening rate of bainitic plate is not con- sistent with Trivedi's model.The thiekening process is only macroscopieally controlled by vol- ume diffusion but its nature is a shear process.展开更多
文摘Semi-implicit direct kinetics(SIDK)is an innovative method for the temporal discretization of neutronic equations proposed by J.Banfield.The key approximation of the SIDK method is to substitute a timeaveraged quantity for the fission source term in the delayed neutron differential equations.Hence,these equations are decoupled from prompt neutron equations and an explicit analytical representation of precursor groups is obtained,which leads to a significant reduction in computational cost.As the fission source is not known in a time step,the original study suggested using a constant quantity pertaining to the previous time step for this purpose,and a reduction in the size of the time step was proposed to lessen the imposed errors.However,this remedy notably diminishes the main advantage of the SIDK method.We discerned that if the original method is properly introduced into the algorithm of the point-implicit solver along with some modifications,the mentioned drawbacks will be mitigated adequately.To test this idea,a novel multigroup,multi-dimensional diffusion code using the finitevolume method and a point-implicit solver is developed which works in both transient and steady states.In addition to the SIDK,two other kinetic methods,i.e.,direct kinetics and higher-order backward discretization,are programmed into the diffusion code for comparison with the proposed model.The final code is tested at different conditions of two well-known transient benchmark problems.Results indicate that while the accuracy of the improved SIDK is closely comparable with the best available kinetic methods,it reduces the total time required for computation by up to 24%.
文摘目的:探讨成人和儿童术前乳酸林格氏液液体动力学的差别。方法:本研究是随机,双盲前瞻性研究。择期盆腔、肛肠或者下肢小手术患者28例,美国麻醉医师协会(ASA)I级,其中儿童14例,成人14例。所有患者给予镇静药后在20 min内恒速输入10 m L/kg的乳酸林格氏液体,通过血红蛋白(Hb)稀释-时间曲线和尿量采用Matlab 4.2软件包计算液体动力学参数。结果:一级动力学模型拟合结果显示,与成人相比,在输入林格氏液体后90 min内儿童的血浆稀释程度明显降低(0.16 vs 0.07,P=0.000),儿童将输入液体的43%通过肾脏排出,显著高于成人(18%)(P=0.011)。按公斤体重计算儿童和成人对乳酸林格氏液的血浆清除率分别是2.2 m L·min-1·kg-1和0.5 m L·min-1·kg-1(P=0.016),而肾脏对乳酸林格氏液体的清除率两组分别是0.76 m L·min-1·kg-1和0.10 m L·min-1·kg-1,(P=0.000)。结论:儿童对乳酸林格氏液体血浆和肾脏清除率分别是成人的4倍和7倍,术前给儿童输液,按照体重计算量可以参照成人的剂量。
基金supported by the National High Technology Research Project“863”under Grant No.2002AA331112the Major Science and Technology Project of Henan Province,China,under Grant No.0122021300.
文摘Precipitation behavior of the early aging stage and the transformation kinetics were studied by analysing the electrical resistance variation of the solution Cu-Ni-Si alloy in the process of aging. Due to the linear relationship between electrical conductivity and volume fraction of precipitates, the transformation kinetics equation can be educed from the Avrami empirical formula, on the basis of this equation, transformation kinetics curve and "C" curve of the isothermal transformation were established.
基金This work was supported by the National High Technology Research Project“863"under Grant No.2002AA331112by the Major Science&Technology Project of Henan Province,China,under Grant No.0122021300.
文摘The aging precipitation behavior in solution treated Cu-Ni-Si-Cr alloy has been studied in terms of the analyses of the variations in electrical conductivity. On the basis of the linear relationship between the electrical conductivity and the volume fraction of the precipitates, the phase transformation kinetics equation was deduced from the Avrami empiricai formula. On the basis of this equation, transformation kinetics curves corresponding to 5% and 50% transformation were established.
基金supported by the National Natural Science Foudation of China(No.50334010)National High Technical Research and Development Programme of China(No.2001AA339030)
文摘On the basis of phase transformation kinetics, the transformation of γ→α,P,B have been investigated through considering the effect of deformation. The calculation methods of volume fraction have also been given. Comparing with common method, the simulated results are in more agreement with experiment results.
文摘In situ observation of the growth process of bainitic plate in βbrass by means of high-temper- ature TEM is conducted.The lengthening and thickening kinetics of bainitic plate is analysed with Trivedi's model and Zener-Hillert's model,respectively.It is found that the stacking fault substructure exists just in the growth tip of fresh bainitie plate and so does the shear stress in the matrix around the tip.The measured lengthening rate of bainitic plate is not con- sistent with Trivedi's model.The thiekening process is only macroscopieally controlled by vol- ume diffusion but its nature is a shear process.
基金the National Natural Science Foundation of China(Nos.51271035 and 51371032)for funding this workfinancial support from the National Natural Science Foundation of China(No.51204092)the Key Laboratory Fundamental Research Project of the Education Department of Liaoning Province,China(No.LZ2015046)
