The dry impact wear behavior of bainite ductile cast iron was evaluated under three different impact loads for 30000 cycles. The strain-hardening effects beneath the contact surfaces were analyzed according to the sur...The dry impact wear behavior of bainite ductile cast iron was evaluated under three different impact loads for 30000 cycles. The strain-hardening effects beneath the contact surfaces were analyzed according to the surfaces' micro-hardness profiles. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to observe the wom surfaces. The results indicated that the material with the highest hardness was the one continuously cooled at 20℃, which exhibited the lowest wear rate under each set of test conditions. The hardness of the worn surface and the thickness of the hardened layer increased with the increases in impact load and in the number of test cycles. The better wear performance of the sample cooled at 20℃ is attributed to its finer microstructure and superior mechanical properties. All the samples underwent the transformation induced plasticity (TRIP) phenomenon after impact wear, as revealed by the fact that small amounts of retained austenite were detected by XRD.展开更多
The deformation behavior and formability of gradient nano-grained(GNG) AISI 304 stainless steel in uniaxial and biaxial states were investigated by means of tensile test and small punch test(SPT). The GNG top laye...The deformation behavior and formability of gradient nano-grained(GNG) AISI 304 stainless steel in uniaxial and biaxial states were investigated by means of tensile test and small punch test(SPT). The GNG top layer was fabricated on coarse grains(CG) AISI 304 by ultrasonic impact treatment. The results showed that the CG substrate could effectively suppress the strain localization of NC in GNG layer, and an approximate linear relationship existed between the thickness of substrate(h) and uniform true strain before necking(ε_(unif)). Grain growth of NC was observed at the stress state with high Stress triaxiality T, which led to better ductility of GNG/CG 304 in SPT, as well as similar true strain after the onset of necking(ε_(neck)) compared with coarse 304 in tensile test. Ei-values of GNG/CG 304 with different structures were nearly the same at different punch speeds, and good formability of GNG/CG 304 was demonstrated. However, punch speed and microstructure needed to be optimized to avoid much lost of membrane strain region in biaxial stress state.展开更多
While animal models of controlled cortical impact often display short-term motor dysfunction after injury, histological examinations do not show severe cortical damage. Thus, this model requires further improvement. M...While animal models of controlled cortical impact often display short-term motor dysfunction after injury, histological examinations do not show severe cortical damage. Thus, this model requires further improvement. Mice were subjected to injury at three severities using a Pin-Point^(TM)-controlled cortical impact device to establish secondary brain injury mouse models. Twenty-four hours after injury, hematoxylin-eosin staining, Fluoro-Jade B histofluorescence, and immunohistochemistry were performed for brain slices. Compared to the uninjured side, we observed differences of histopathological findings, neuronal degeneration, and glial cell number in the CA2 and CA3 regions of the hippocampus on the injured side. The Morris water maze task and beam-walking test verified long-term(14–28 days) spatial learning/memory and motor balance. To conclude, the histopathological responses were positively correlated with the degree of damage,as were the long-term behavioral manifestations after controlled cortical impact. All animal procedures were approved by the Institutional Animal Care and Use Committee at Shanghai Jiao Tong University School of Medicine.展开更多
Annular grooved projectiles(AGPs)have drawn ongoing concerns as an advanced penetrator for their excellent anti-rebound capability in impacting metal plates.They could become embedded solidly in the target surface dur...Annular grooved projectiles(AGPs)have drawn ongoing concerns as an advanced penetrator for their excellent anti-rebound capability in impacting metal plates.They could become embedded solidly in the target surface during low-velocity impact.In this investigation,the firm embedding behavior of AGP was observed by impact experiments.Corresponding numerical simulations provided a better understanding of this process.Experimental and numerical results indicated that the firm embedding behavior of AGP was mainly due to the filling-material in the groove rather than the friction between the projectile and target,unlike traditional shape such as conical projectile.According to observation,firm embedding process can generally be subdivided into four stages:initial-cratering stage,groove-filling stage,fillingmaterial failure stage and rebound vibration stage.Moreover,the damage mechanics of target material around crater was obtained through microscopic tests.A comparison of the cross-sectional figures between the experiment and simulation proved that the analysis and the proposed method were reasonable and feasible,which further demonstrated that the firm embedding behavior has application potential in new concept warheads.展开更多
The mechanical behavior of TiNi alloy and Cr12MoV alloy under dynamic impact loading was investigated with a self-made impact testing system. The real-time contact force was measured with a piezoelectric force sensor ...The mechanical behavior of TiNi alloy and Cr12MoV alloy under dynamic impact loading was investigated with a self-made impact testing system. The real-time contact force was measured with a piezoelectric force sensor and digital signal processing system during impact. Equations for predicting instantaneous velocity anti displacement were presented. The results showed that the TiNi alloy exhibited a plateau of maximum contact force with increasing impact height. At the plateau stage, TiNi alloy in the parent phase can absorb impact energy and keep the maximum contact force nearly identical due to its pseudoelasticity.展开更多
Fracture behavior of CrN coatings deposited on the surface of silicon and AISI52100 steel by different energy ion beam assisted magnetron sputtering technique (IBAMS) was studied using indentation and dynamic cycle ...Fracture behavior of CrN coatings deposited on the surface of silicon and AISI52100 steel by different energy ion beam assisted magnetron sputtering technique (IBAMS) was studied using indentation and dynamic cycle impact. It is found that, for the coatings on silicon substrate, the cracks form in the indentation corners and then propagate outward under Vickers indentation. The coating prepared using ion assisted energy of 800 eV shows the highest fracture resistance due to its compact structure. Under Rockwell indentation, only finer radial cracks are found in the CrN coating on AISI 52100 steel without ion assisting while in the condition of ion assisting energy of 800 eV, radial, lateral cracks and spalling appear in the vicinity of indentation. The fracture of CrN coatings under dynamic cycle impact is similar to fatigue. The impact fracture resistance of CrN coatings increases with the increase of ion assisting energy.展开更多
The compressive properties of epoxy with different silica nanoparticles (SiO2 nanoparticles) contents at quasi-static and high strain rates loading were investigated via experiment. This article evaluates the compress...The compressive properties of epoxy with different silica nanoparticles (SiO2 nanoparticles) contents at quasi-static and high strain rates loading were investigated via experiment. This article evaluates the compressive failure behaviors and modes at different SiO2 nanoparticles contents and different strain rates. The results indicated that the stress strain curves were sensitive to strain rate, and the compressive failure stress of composites with various SiO2 nanoparticles contents increased with the strain rates, and it increased along with SiO2 nanoparticles contents and then declined. The compressive failure stress and the compressive failure modes of the composites were apparently different from the change of SiO2 nanoparticles contents.展开更多
The counter-intuitive behaviors of pin-ended beams under the projectile impact axe investigated with ANSYS/LS-DYNA in this paper. It studies in detail their displacement-time history curves, final deformed shapes, ene...The counter-intuitive behaviors of pin-ended beams under the projectile impact axe investigated with ANSYS/LS-DYNA in this paper. It studies in detail their displacement-time history curves, final deformed shapes, energy relationships and projectile impact velocity ranges related to their counter-intuitive behaviors. The influences of the impact positions on their counterintuitive behaviors are also discussed. The results show that no matter where the impact position on the beam is, the counter-intuitive behaviors of pinned beams will occur as long as the impacting velocity lies within a proper range. Corresponding to the occurring of the counter-intuitive behaviors, the rebounding number in the displacement history curves of the beams decreases from a few times to zero with an increase of the impact velocity. The final deformation modes of the beam corresponding to the counter-intuitive behaviors will appear in symmetrical and unsymmetrical forms no matter where the impact position is; the impact velocity of the first-occurring of the counter-intuitive behaviors of the beam increases slowly with the deviation of the impact position away from the mid-span.展开更多
目的分析基于IMPACT模式的护理管理结合低升糖指数膳食管理对2型糖尿病(T2DM)患者饮食行为及自护能力的影响。方法选取2021年1月至12月收治的100例T2DM患者为研究对象,按照随机数字表法将其分为对照组与观察组,各50例。对照组采用常规...目的分析基于IMPACT模式的护理管理结合低升糖指数膳食管理对2型糖尿病(T2DM)患者饮食行为及自护能力的影响。方法选取2021年1月至12月收治的100例T2DM患者为研究对象,按照随机数字表法将其分为对照组与观察组,各50例。对照组采用常规护理干预,观察组在对照组基础上加基于IMPACT模式的护理管理结合低升糖指数膳食管理。比较两组的饮食行为、自护能力以及血糖控制水平。结果干预后,观察组的饮食行为量表各维度评分高于对照组,差异具有统计学意义(P<0.05)。干预后,观察组的自我护理能力测定量表(ESCA)各维度评分高于对照组,差异具有统计学意义(P<0.05)。干预后,观察组的空腹血糖(FBG)、餐后2 h血糖(2 h PBG)水平低于对照组,差异具有统计学意义(P<0.05)。结论基于IMPACT模式的护理管理结合低升糖指数膳食管理不仅能够改变患者饮食行为,还能加强其自护能力,以此提高血糖控制水平,值得推广。展开更多
近年来,业务流程的精确管理受到越来越多的关注,作为业务流程管理内容之一的一致性检查技术正变得越来越重要。现有的一致性检查技术主要从模型的控制流角度出发,并未考虑业务流程中的数据或数据的变化对业务流程产生的影响,为此提出了...近年来,业务流程的精确管理受到越来越多的关注,作为业务流程管理内容之一的一致性检查技术正变得越来越重要。现有的一致性检查技术主要从模型的控制流角度出发,并未考虑业务流程中的数据或数据的变化对业务流程产生的影响,为此提出了一种基于数据影响的业务流程一致性检查方法。首先,通过业务流程建模符号(business process modeling notation,BPMN)模型中数据和行为之间的依赖关系来分析数据对偏差活动预期行为的影响,进而获取偏差活动的预期行为集;其次,通过在BPMN模型中引入决策模型和符号(decision model and notation,DMN)决策表来充分捕获当前实例执行的数据上下文与行为上下文之间的关系,以区分有效数据更改和异常数据更改,找到偏差活动的有效预期行为集。最后,通过设计数据对偏差活动影响的各类成本函数提出了有效一致性检查方法。实验结果表明,相比已有工作,该方法在进行业务流程一致性检查时提高了业务流程的一致性,可以成功捕获偏差活动作出反应的适应行为,使得业务流程在复杂多变的环境下表现得更加准确、合理。展开更多
文摘The dry impact wear behavior of bainite ductile cast iron was evaluated under three different impact loads for 30000 cycles. The strain-hardening effects beneath the contact surfaces were analyzed according to the surfaces' micro-hardness profiles. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to observe the wom surfaces. The results indicated that the material with the highest hardness was the one continuously cooled at 20℃, which exhibited the lowest wear rate under each set of test conditions. The hardness of the worn surface and the thickness of the hardened layer increased with the increases in impact load and in the number of test cycles. The better wear performance of the sample cooled at 20℃ is attributed to its finer microstructure and superior mechanical properties. All the samples underwent the transformation induced plasticity (TRIP) phenomenon after impact wear, as revealed by the fact that small amounts of retained austenite were detected by XRD.
基金Funded by the National National Natural Science Foundation of China(No.51505189)Open Project of Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment&Technology(No.FM-2015-5)
文摘The deformation behavior and formability of gradient nano-grained(GNG) AISI 304 stainless steel in uniaxial and biaxial states were investigated by means of tensile test and small punch test(SPT). The GNG top layer was fabricated on coarse grains(CG) AISI 304 by ultrasonic impact treatment. The results showed that the CG substrate could effectively suppress the strain localization of NC in GNG layer, and an approximate linear relationship existed between the thickness of substrate(h) and uniform true strain before necking(ε_(unif)). Grain growth of NC was observed at the stress state with high Stress triaxiality T, which led to better ductility of GNG/CG 304 in SPT, as well as similar true strain after the onset of necking(ε_(neck)) compared with coarse 304 in tensile test. Ei-values of GNG/CG 304 with different structures were nearly the same at different punch speeds, and good formability of GNG/CG 304 was demonstrated. However, punch speed and microstructure needed to be optimized to avoid much lost of membrane strain region in biaxial stress state.
基金supported by the National Natural Science Foundation of China,No.81771332,81571184,81070990(all to CLZ)the Shanghai Key Medical Discipline for Critical Care Medicine of China,No.2017zz02017(to CLZ)+1 种基金the Key Discipline Construction Project of Pudong Health Bureau of Shanghai of China,No.PWZxk2017-23,PWYgf2018-05(both to CLZ)the Outstanding Leaders Training Program of Pudong Health Bureau of Shanghai of China,No.PWR12018-07(to CLZ)
文摘While animal models of controlled cortical impact often display short-term motor dysfunction after injury, histological examinations do not show severe cortical damage. Thus, this model requires further improvement. Mice were subjected to injury at three severities using a Pin-Point^(TM)-controlled cortical impact device to establish secondary brain injury mouse models. Twenty-four hours after injury, hematoxylin-eosin staining, Fluoro-Jade B histofluorescence, and immunohistochemistry were performed for brain slices. Compared to the uninjured side, we observed differences of histopathological findings, neuronal degeneration, and glial cell number in the CA2 and CA3 regions of the hippocampus on the injured side. The Morris water maze task and beam-walking test verified long-term(14–28 days) spatial learning/memory and motor balance. To conclude, the histopathological responses were positively correlated with the degree of damage,as were the long-term behavioral manifestations after controlled cortical impact. All animal procedures were approved by the Institutional Animal Care and Use Committee at Shanghai Jiao Tong University School of Medicine.
基金This paper was supported by National 863 Program (2002AA245141)national Foundation of Application of Agricul-tural Scientific and Technological Achievements (2006GB23600450)
基金financially supported by the National Natural Science Foundation of China [grant number 11472053]
文摘Annular grooved projectiles(AGPs)have drawn ongoing concerns as an advanced penetrator for their excellent anti-rebound capability in impacting metal plates.They could become embedded solidly in the target surface during low-velocity impact.In this investigation,the firm embedding behavior of AGP was observed by impact experiments.Corresponding numerical simulations provided a better understanding of this process.Experimental and numerical results indicated that the firm embedding behavior of AGP was mainly due to the filling-material in the groove rather than the friction between the projectile and target,unlike traditional shape such as conical projectile.According to observation,firm embedding process can generally be subdivided into four stages:initial-cratering stage,groove-filling stage,fillingmaterial failure stage and rebound vibration stage.Moreover,the damage mechanics of target material around crater was obtained through microscopic tests.A comparison of the cross-sectional figures between the experiment and simulation proved that the analysis and the proposed method were reasonable and feasible,which further demonstrated that the firm embedding behavior has application potential in new concept warheads.
文摘The mechanical behavior of TiNi alloy and Cr12MoV alloy under dynamic impact loading was investigated with a self-made impact testing system. The real-time contact force was measured with a piezoelectric force sensor and digital signal processing system during impact. Equations for predicting instantaneous velocity anti displacement were presented. The results showed that the TiNi alloy exhibited a plateau of maximum contact force with increasing impact height. At the plateau stage, TiNi alloy in the parent phase can absorb impact energy and keep the maximum contact force nearly identical due to its pseudoelasticity.
基金Funded by the National Natural Science Foundation of China(No. 50771070)Shanxi Province Science and Technology Key Projects (No. 20100321078-02)
文摘Fracture behavior of CrN coatings deposited on the surface of silicon and AISI52100 steel by different energy ion beam assisted magnetron sputtering technique (IBAMS) was studied using indentation and dynamic cycle impact. It is found that, for the coatings on silicon substrate, the cracks form in the indentation corners and then propagate outward under Vickers indentation. The coating prepared using ion assisted energy of 800 eV shows the highest fracture resistance due to its compact structure. Under Rockwell indentation, only finer radial cracks are found in the CrN coating on AISI 52100 steel without ion assisting while in the condition of ion assisting energy of 800 eV, radial, lateral cracks and spalling appear in the vicinity of indentation. The fracture of CrN coatings under dynamic cycle impact is similar to fatigue. The impact fracture resistance of CrN coatings increases with the increase of ion assisting energy.
文摘The compressive properties of epoxy with different silica nanoparticles (SiO2 nanoparticles) contents at quasi-static and high strain rates loading were investigated via experiment. This article evaluates the compressive failure behaviors and modes at different SiO2 nanoparticles contents and different strain rates. The results indicated that the stress strain curves were sensitive to strain rate, and the compressive failure stress of composites with various SiO2 nanoparticles contents increased with the strain rates, and it increased along with SiO2 nanoparticles contents and then declined. The compressive failure stress and the compressive failure modes of the composites were apparently different from the change of SiO2 nanoparticles contents.
基金Project supported by Shanxi Province Returned Scholars Fund (No.200335).
文摘The counter-intuitive behaviors of pin-ended beams under the projectile impact axe investigated with ANSYS/LS-DYNA in this paper. It studies in detail their displacement-time history curves, final deformed shapes, energy relationships and projectile impact velocity ranges related to their counter-intuitive behaviors. The influences of the impact positions on their counterintuitive behaviors are also discussed. The results show that no matter where the impact position on the beam is, the counter-intuitive behaviors of pinned beams will occur as long as the impacting velocity lies within a proper range. Corresponding to the occurring of the counter-intuitive behaviors, the rebounding number in the displacement history curves of the beams decreases from a few times to zero with an increase of the impact velocity. The final deformation modes of the beam corresponding to the counter-intuitive behaviors will appear in symmetrical and unsymmetrical forms no matter where the impact position is; the impact velocity of the first-occurring of the counter-intuitive behaviors of the beam increases slowly with the deviation of the impact position away from the mid-span.
文摘目的分析基于IMPACT模式的护理管理结合低升糖指数膳食管理对2型糖尿病(T2DM)患者饮食行为及自护能力的影响。方法选取2021年1月至12月收治的100例T2DM患者为研究对象,按照随机数字表法将其分为对照组与观察组,各50例。对照组采用常规护理干预,观察组在对照组基础上加基于IMPACT模式的护理管理结合低升糖指数膳食管理。比较两组的饮食行为、自护能力以及血糖控制水平。结果干预后,观察组的饮食行为量表各维度评分高于对照组,差异具有统计学意义(P<0.05)。干预后,观察组的自我护理能力测定量表(ESCA)各维度评分高于对照组,差异具有统计学意义(P<0.05)。干预后,观察组的空腹血糖(FBG)、餐后2 h血糖(2 h PBG)水平低于对照组,差异具有统计学意义(P<0.05)。结论基于IMPACT模式的护理管理结合低升糖指数膳食管理不仅能够改变患者饮食行为,还能加强其自护能力,以此提高血糖控制水平,值得推广。
文摘近年来,业务流程的精确管理受到越来越多的关注,作为业务流程管理内容之一的一致性检查技术正变得越来越重要。现有的一致性检查技术主要从模型的控制流角度出发,并未考虑业务流程中的数据或数据的变化对业务流程产生的影响,为此提出了一种基于数据影响的业务流程一致性检查方法。首先,通过业务流程建模符号(business process modeling notation,BPMN)模型中数据和行为之间的依赖关系来分析数据对偏差活动预期行为的影响,进而获取偏差活动的预期行为集;其次,通过在BPMN模型中引入决策模型和符号(decision model and notation,DMN)决策表来充分捕获当前实例执行的数据上下文与行为上下文之间的关系,以区分有效数据更改和异常数据更改,找到偏差活动的有效预期行为集。最后,通过设计数据对偏差活动影响的各类成本函数提出了有效一致性检查方法。实验结果表明,相比已有工作,该方法在进行业务流程一致性检查时提高了业务流程的一致性,可以成功捕获偏差活动作出反应的适应行为,使得业务流程在复杂多变的环境下表现得更加准确、合理。