The response of three-dimensional sample of Al, containing vacancy complex, under shear loading was simulated. The molecular dynamics method was used and interaction between atoms was described on the base of pseudopo...The response of three-dimensional sample of Al, containing vacancy complex, under shear loading was simulated. The molecular dynamics method was used and interaction between atoms was described on the base of pseudopotential theory Solitary waves were generated in the sample under mechanical loading. Their interaction with the vacancy complexes was shown to be able to initiate hot spot in that local region of the complexes. Some parameters of the hot spot as well as solitary waves were calculated. The initiation of the hot spot is accompanied with sufficient local structural relaxation.展开更多
The effect of strain rate on the tensile strength of defective monocrystalline silicon （Si） nanorods is studied with the molecular dynamics method. The strain rate applied to the nanorods is varied from l0T to 1014 ...The effect of strain rate on the tensile strength of defective monocrystalline silicon （Si） nanorods is studied with the molecular dynamics method. The strain rate applied to the nanorods is varied from l0T to 1014 s-1, and the atomic interactions among the Si atoms are described by the Stillinger-Weber （SW） potential functions. The tensile strength of the ideal Si nanorod is shown to be strongly strain rate dependent and increasing with the strain rate. The failure pattern also shows strain rate dependence, indicating that increased strain rates gradually suppress unsuitable relaxation and dissipation mechanisms because of the accompanying larger external loadings. Furthermore, the effects of intrinsic material parameters （i.e., the cutoff radius of SW potential function） and defects （i.e., inevitable surface defects and internal preinstalled defects） are investigated. It is revealed that the effect of strain rate on the tensile strength of Si nanorod is influenced by both the intrinsic physical properties of the material and the distribution of the initial defects, with specific surface defects appearing to be more important to nanostructure design.展开更多
针对复合材料电池包下箱体的树脂传递模塑(Resin Transfer Molding,RTM)成型进行了方案设计,基于PAM-RTM软件对其充模过程进行仿真分析及孔隙缺陷预测。首先,对比了两种方案在三种出胶口状态下充模时间,分析了注胶压力及树脂黏度对RTM...针对复合材料电池包下箱体的树脂传递模塑(Resin Transfer Molding,RTM)成型进行了方案设计,基于PAM-RTM软件对其充模过程进行仿真分析及孔隙缺陷预测。首先,对比了两种方案在三种出胶口状态下充模时间,分析了注胶压力及树脂黏度对RTM成型时间的影响规律;其次,分析了充模过程中注胶口附近位置的压力变化情况;最后,预测了宏观/微观两种尺度孔隙缺陷在构件中分布及注胶压力对孔隙含量的影响规律,并结合流速优化理论控制树脂前沿流速以降低孔隙含量。结果表明,模腔内注胶与出胶口压力差越大,成型用时越少,且受到注胶位置影响。注胶压力与充模时间呈线性关系,压力越低,充模时间缩短效果越明显,且黏度越大,充模时间越长。孔隙含量与前沿流速有关,注胶压力越大导致流速越快,宏观孔隙随之减少,微观孔隙相应增多;且流速优化方式注胶能够显著降低总体孔隙率水平,但会延长成型周期。展开更多
With the application of X-ray computed tomography（CT） technology of C80 high-strength concrete with polypropylene fiber at elevated temperatures, the microscopic damage evolution process observation and image buildi...With the application of X-ray computed tomography（CT） technology of C80 high-strength concrete with polypropylene fiber at elevated temperatures, the microscopic damage evolution process observation and image building could be obtained, based on the statistics theory and numerical analysis of the combination of concrete internal defects extension and evolution regularity of microscopic structure. The expermental results show that the defect rate has changed at different temperatures and can determine the concrete degradation threshold temperatures. Also, data analysis can help to establish the evolution equation between the defect rate and the effect of temperature damage, and identify that the addition of polypropylene fibers in the high strength concrete at high temperature can improve cracking resistance.展开更多
This paper considers a model regarding the products with finite life which allows defective items in reproduction and causes a small amount of decay. The market demand is assumed to be level dependent linear type. The...This paper considers a model regarding the products with finite life which allows defective items in reproduction and causes a small amount of decay. The market demand is assumed to be level dependent linear type. The model has also considered the constant production rate which stops after a desired level of inventories and that is the highest level of it. Due to the market demand, defective item and product’s decay, the inventory reduces to the zero level where again the production cycle starts. With a numerical search procedure</span><span style="font-size:12px;font-family:Verdana;">,</span><span style="font-size:12px;font-family:Verdana;"> the proof of the proposed model has been shown. The objective of the proposed model is to find out the total optimum inventory cost, optimum ordering cost and optimum ordering cycle.展开更多
Background: In pseudoexfoliative syndrome (PEX), extraocular accumulation is associated with cardiovascular morbidity and mortality. The aim of this study was to investigate the effect of exercise test on corrected QT...Background: In pseudoexfoliative syndrome (PEX), extraocular accumulation is associated with cardiovascular morbidity and mortality. The aim of this study was to investigate the effect of exercise test on corrected QT dispersion (QTcd) and QTcd recovery in PEX. Patients and Methods: A total of 37 patients diagnosed as PEX were included in the study. The control group consisted of 38 patients. The Electrocardiographies (ECG) were taken. The patients were subjected to an exercise test. Results: In the study group, baseline, peak and third minute recovery QTcd values were 41.35 ± 7.27 ms, 65.19 ± 7.83 ms, and 53.61 ± 6.45 ms, respectively. In the control group, baseline, peak and third minute recovery QTcd values were 29.92 ± 4.23 ms, 38.31 ± 4.22 ms and 28.76 ± 3.09 ms, respectively. There was statistically significant?difference between the baseline and peak QTcd values of the study group and?the control group (t = 8.34224/p 0.00001, t = 18.55079/p 0.00001, respectively). In addition, while there was a statistically significant?difference between the baseline QTcd and the third minute recovery QTcd in the study group, there was no statistically significant difference between the baseline QTcd value and the third minute recovery QTcd value in the control group as heart rate recovery (t = 8.388558/p 0.00001, t = 1.967315/p = 0.056668, respectively).?Conclusion: All of them were found to have a higher risk in terms of malignant ventricular arrhythmia in the study group, both at rest and with effort, in a statistically significant way compared to the control group.展开更多
文摘The response of three-dimensional sample of Al, containing vacancy complex, under shear loading was simulated. The molecular dynamics method was used and interaction between atoms was described on the base of pseudopotential theory Solitary waves were generated in the sample under mechanical loading. Their interaction with the vacancy complexes was shown to be able to initiate hot spot in that local region of the complexes. Some parameters of the hot spot as well as solitary waves were calculated. The initiation of the hot spot is accompanied with sufficient local structural relaxation.
基金supported by National Basic Research Program of China(No.2013CB035902)Research Project of State Key Laboratory of Hydroscience and Engineering of Tsinghua University(No.2011-KY-4)the National Natural Science Foundation of China(Nos.51339033 and 51279087)
文摘The effect of strain rate on the tensile strength of defective monocrystalline silicon （Si） nanorods is studied with the molecular dynamics method. The strain rate applied to the nanorods is varied from l0T to 1014 s-1, and the atomic interactions among the Si atoms are described by the Stillinger-Weber （SW） potential functions. The tensile strength of the ideal Si nanorod is shown to be strongly strain rate dependent and increasing with the strain rate. The failure pattern also shows strain rate dependence, indicating that increased strain rates gradually suppress unsuitable relaxation and dissipation mechanisms because of the accompanying larger external loadings. Furthermore, the effects of intrinsic material parameters （i.e., the cutoff radius of SW potential function） and defects （i.e., inevitable surface defects and internal preinstalled defects） are investigated. It is revealed that the effect of strain rate on the tensile strength of Si nanorod is influenced by both the intrinsic physical properties of the material and the distribution of the initial defects, with specific surface defects appearing to be more important to nanostructure design.
文摘针对复合材料电池包下箱体的树脂传递模塑(Resin Transfer Molding,RTM)成型进行了方案设计,基于PAM-RTM软件对其充模过程进行仿真分析及孔隙缺陷预测。首先,对比了两种方案在三种出胶口状态下充模时间,分析了注胶压力及树脂黏度对RTM成型时间的影响规律;其次,分析了充模过程中注胶口附近位置的压力变化情况;最后,预测了宏观/微观两种尺度孔隙缺陷在构件中分布及注胶压力对孔隙含量的影响规律,并结合流速优化理论控制树脂前沿流速以降低孔隙含量。结果表明,模腔内注胶与出胶口压力差越大,成型用时越少,且受到注胶位置影响。注胶压力与充模时间呈线性关系,压力越低,充模时间缩短效果越明显,且黏度越大,充模时间越长。孔隙含量与前沿流速有关,注胶压力越大导致流速越快,宏观孔隙随之减少,微观孔隙相应增多;且流速优化方式注胶能够显著降低总体孔隙率水平,但会延长成型周期。
基金Funded by the National Natural Science Foundation of China(No.51278325)the Shanxi Province Natural Science Foundation(No.2011011024-2)
文摘With the application of X-ray computed tomography（CT） technology of C80 high-strength concrete with polypropylene fiber at elevated temperatures, the microscopic damage evolution process observation and image building could be obtained, based on the statistics theory and numerical analysis of the combination of concrete internal defects extension and evolution regularity of microscopic structure. The expermental results show that the defect rate has changed at different temperatures and can determine the concrete degradation threshold temperatures. Also, data analysis can help to establish the evolution equation between the defect rate and the effect of temperature damage, and identify that the addition of polypropylene fibers in the high strength concrete at high temperature can improve cracking resistance.
文摘This paper considers a model regarding the products with finite life which allows defective items in reproduction and causes a small amount of decay. The market demand is assumed to be level dependent linear type. The model has also considered the constant production rate which stops after a desired level of inventories and that is the highest level of it. Due to the market demand, defective item and product’s decay, the inventory reduces to the zero level where again the production cycle starts. With a numerical search procedure</span><span style="font-size:12px;font-family:Verdana;">,</span><span style="font-size:12px;font-family:Verdana;"> the proof of the proposed model has been shown. The objective of the proposed model is to find out the total optimum inventory cost, optimum ordering cost and optimum ordering cycle.
文摘Background: In pseudoexfoliative syndrome (PEX), extraocular accumulation is associated with cardiovascular morbidity and mortality. The aim of this study was to investigate the effect of exercise test on corrected QT dispersion (QTcd) and QTcd recovery in PEX. Patients and Methods: A total of 37 patients diagnosed as PEX were included in the study. The control group consisted of 38 patients. The Electrocardiographies (ECG) were taken. The patients were subjected to an exercise test. Results: In the study group, baseline, peak and third minute recovery QTcd values were 41.35 ± 7.27 ms, 65.19 ± 7.83 ms, and 53.61 ± 6.45 ms, respectively. In the control group, baseline, peak and third minute recovery QTcd values were 29.92 ± 4.23 ms, 38.31 ± 4.22 ms and 28.76 ± 3.09 ms, respectively. There was statistically significant?difference between the baseline and peak QTcd values of the study group and?the control group (t = 8.34224/p 0.00001, t = 18.55079/p 0.00001, respectively). In addition, while there was a statistically significant?difference between the baseline QTcd and the third minute recovery QTcd in the study group, there was no statistically significant difference between the baseline QTcd value and the third minute recovery QTcd value in the control group as heart rate recovery (t = 8.388558/p 0.00001, t = 1.967315/p = 0.056668, respectively).?Conclusion: All of them were found to have a higher risk in terms of malignant ventricular arrhythmia in the study group, both at rest and with effort, in a statistically significant way compared to the control group.
