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The Effect of Ginkgo Biloba Leaf Dropping Pill Combined with Butylphthalide Capsule on Cognitive Dysfunction in Patients after Acute Ischemic Stroke and Its Impact on Serum Cytokines
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作者 Yaojie Cai Yuping He +1 位作者 Gang Yang Yan Chen 《Journal of Biosciences and Medicines》 2024年第7期252-262,共11页
Objective: To investigate the therapeutic effect of Ginkgo biloba extract dropping pills combined with butylphthalide capsules on cognitive dysfunction in patients after acute ischemic stroke (AIS) and its impact on s... Objective: To investigate the therapeutic effect of Ginkgo biloba extract dropping pills combined with butylphthalide capsules on cognitive dysfunction in patients after acute ischemic stroke (AIS) and its impact on serum cytokines CRP, IL-6, and Hcy. Methods: This study selected 76 patients with cognitive dysfunction after ischemic stroke who were hospitalized at Zhuji People’s Hospital from January 2023 to January 2024. The patients were divided into two groups. The control group was treated with butylphthalide capsules, while the combination group received Ginkgo biloba extract dropping pills in addition to the treatment given to the control group. The neurological function, cognitive function, activities of daily living, and levels of serum cytokines CRP, IL-6, and Hcy were compared between the two groups after 1 month and 3 months of treatment. Results: The NIHSS scores, MMSE scores, ADL scores, and levels of CRP, IL-6, and Hcy in both groups showed statistically significant differences compared to before treatment (P Conclusion: The combination of Ginkgo biloba extract dropping pills and butylphthalide capsules has a better therapeutic effect on cognitive dysfunction in patients after ischemic stroke. It can improve the neurological function and cognitive function of patients, enhance their ability to perform daily activities, and reduce inflammatory responses. 展开更多
关键词 Acute Ischemic Stroke Ginkgo Biloba Leaf drop Pills Butylphthalein Cognitive Impairment
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美国教师评估与退出机制的构建及其启示:基于对IMPACT教师评估系统的剖析
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作者 王莹 任霞 《成都师范学院学报》 2024年第4期43-54,共12页
为探索我国教师评估与退出机制的建立与运行,采用文本分析方法对美国华盛顿哥伦比亚特区IMPACT评估系统操作指南进行分析,总结IMPACT评估系统的运行体系与特点,为我国教师评估与退出机制提供借鉴。IMPACT评估系统通过覆盖全体的评估对... 为探索我国教师评估与退出机制的建立与运行,采用文本分析方法对美国华盛顿哥伦比亚特区IMPACT评估系统操作指南进行分析,总结IMPACT评估系统的运行体系与特点,为我国教师评估与退出机制提供借鉴。IMPACT评估系统通过覆盖全体的评估对象、专业多元的评估责任主体、丰富具体的评估内容、清晰透明的评估流程以及奖罚分明的评估结果对华盛顿特区公立学校系统教师进行评估,整个系统呈现出评估内容专业化、评估过程公正化、评估结果差异化和评估系统动态化等特点。综观IMPACT评估系统的设计与运行,我国在构建教师评估与退出机制时,应注意在体系建设上强调政府提供制度支持;在评估内容与标准上关注教师能力;在评估责任主体上要兼顾多方利益群体;在系统设计上要因地制宜;最后在系统实施过程中更要注重宽严适度。 展开更多
关键词 impact教师评估系统 华盛顿哥伦比亚特区公立学校系统 教育评估 教师队伍建设 教师退出机制 美国教师
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Numerical simulation of drop weight impact sensitivity evaluation criteria for pressed PBXs 被引量:1
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作者 Hong-zheng Duan Yan-qing Wu +1 位作者 Kun Yang Feng-lei Huang 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第1期76-90,共15页
A thorough understanding of drop-weight impacted responses for polymer-bonded explosives(PBXs)is significant to evaluate their impact sensitivity.The characteristics of the drop-weight impacted pressed PBXs including ... A thorough understanding of drop-weight impacted responses for polymer-bonded explosives(PBXs)is significant to evaluate their impact sensitivity.The characteristics of the drop-weight impacted pressed PBXs including deforming,fracturing,forming a local high-temperature region and igniting,were simulated using a coupled mechanical-thermo-chemical model integrating micro-defects evolution.A novel evaluation method for impact sensitivity is established using the relation between the input kinetic energy and the output energy due to deformation,crushing energy,local hot spot energy and ignition.The effects of impact velocity on sensitivity were analyzed and the critical local ignition impact velocity is determined as 4.0-4.5 m/s.The simulated results show that shear-crack friction heating is the dominant ignition mechanism.The region along the boundary of PBXs sample is the most hazardous regions where ignition first occur.The propagation of stress wave in PBXs causes shear-crack hotspot and bulk temperature exhibiting an approximate 45°direction evolution path,which is the main reason that dominated damage-ignition region transits from the boundary to the central of sample. 展开更多
关键词 Polymer-bonded explosives(PBXs) drop weight impact Numerical simulation Sensitivity evaluation criterion Hotspot mechanism
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Damage response of conventionally reinforced two-way spanning concrete slab under eccentric impacting drop weight loading 被引量:2
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作者 S.M.Anas Mehtab Alam Mohd Shariq 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第1期12-34,共23页
Reinforced concrete(RC)structures are generally designed to carry quasi-static gravity loads through almost indispensable components namely slab,however,it may be subjected to high intense loads induced from the impac... Reinforced concrete(RC)structures are generally designed to carry quasi-static gravity loads through almost indispensable components namely slab,however,it may be subjected to high intense loads induced from the impact of projectiles generated by the tornado,falling construction equipment,and also from accidental explosions during their construction and service lifespan.Impacts due to rock/boulder falls do occur on the structures located especially in hilly areas.Such loadings are not predictable but may cause severe damage to the slab/structure.It stimulates structural engineers and researchers to investigate and understand the dynamic response of RC structures under such impulsive loading.This research work first investigates the performance of 1000×1000×75 mm^(3)conventionally reinforced two-way spanning normal strength concrete slab with only tension reinforcement(0.88%)under the concentric impact load(1035 N)using the finite element method based computer code,ABAQUS/Explicit-v.6.15.The impact load is delivered to the centroid of the slab using a solid-steel cylindroconical impactor(drop weight)with a flat nose of diameter 40 mm,having a total mass of 105 kg released from a fixed height of 2500 mm.Two popular concrete constitutive models in ABAQUS namely;Holmquist-Johnson-Cook(HJC)and Concrete Damage Plasticity(CDP),with strain rate effects as per fib MODEL CODE 2010,are used to model the concrete material behavior to impact loading and to simulate the damage to the slab.The slab response using these two models is analyzed and compared with the impact test results.The strain rate effect on the reinforcing steel bars has been incorporated in the analysis using the Malvar and Crawford(1998)approach.A classical elastoplastic kinematic idealization is considered to model the steel impactor and support system.Results reveal that the HJC model gives a little overestimation of peak displacement,maximum acceleration,and damage of the slab while the predictions given by the CDP model are in reasonable agreement with the experimental test results/observations available in the open literature.Following the validation of the numerical model,analyses have been extended to further investigate the damage response of the slab under eccentric impact loadings.In addition to the concentric location(P1)of the impacting device,five locations on a quarter of the slab i.e.,two along the diagonal(P2&P3),the other two along the mid-span(P4&P5),and the last one(P6)between P3 and P5,covering the entire slab,are considered.Computational results have been discussed and compared,and the evaluation of the most damaging location(s)of the impact is investigated.It has been found that the most critical location of the impact is not the centroid of the slab but the eccentric one with the eccentricity of 1/6th of the span from the centroid along the mid-span section. 展开更多
关键词 RC slabs impact loading Eccentric impacts Concrete models Finite element analysis Damage profiles Stresses Peak acceleration Failure modes Damage dissipation energy CRACKING drop-weight locations
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废冰箱回收利用环境效益评估——基于IMPACT WORLD+方法
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作者 黄银 余茜 +2 位作者 黄瑶 秦晋川 陈梦君 《中国环境科学》 EI CAS CSCD 北大核心 2024年第9期5313-5320,共8页
废电器是产生量大且增速快的一类固体废物.我国构建的废电器回收体系是实施碳达峰?碳中和的重要举措,但废电器回收利用体系的环境效益尚不清楚.利用IMPACTWORLD+方法,从不同环境影响类型出发评估废电器回收处理的环境效益,并通过损害类... 废电器是产生量大且增速快的一类固体废物.我国构建的废电器回收体系是实施碳达峰?碳中和的重要举措,但废电器回收利用体系的环境效益尚不清楚.利用IMPACTWORLD+方法,从不同环境影响类型出发评估废电器回收处理的环境效益,并通过损害类型指标量化评价.结果表明,废冰箱回收利用的损害类型指标“人体健康”和“生态环境质量”的结果分别为-10592.501EUR2015和-8211.357EUR2015,合计为-18803.857EUR2015,即环境收益相当于18803.857EUR2015.据此估算,中国2021年废电器回收处理体系中仅废冰箱回收利用的环境收益可达12.82亿EUR2015.研究结果表明废电器回收处理的环境收益十分可观,有望为废电器回收行业的可持续发展提供新的助力. 展开更多
关键词 废冰箱 生命周期评价 impact WORLD+ 环境效益 环境收益
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Effects of projectile parameters on the momentum transfer and projectile melting during hypervelocity impact 被引量:1
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作者 Wenjin Liu Qingming Zhang +6 位作者 Renrong Long Zizheng Gong Ren Jiankang Xin Hu Siyuan Ren Qiang Wu Guangming Song 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第2期89-103,共15页
The effects of projectile/target impedance matching and projectile shape on energy,momentum transfer and projectile melting during collisions are investigated by numerical simulation.By comparing the computation resul... The effects of projectile/target impedance matching and projectile shape on energy,momentum transfer and projectile melting during collisions are investigated by numerical simulation.By comparing the computation results with the experimental results,the correctness of the calculation and the statistical method of momentum transfer coefficient is verified.Different shapes of aluminum,copper and heavy tungsten alloy projectiles striking aluminum,basalt,and pumice target for impacts up to 10 km/s are simulated.The influence mechanism of the shape of the projectile and projectile/target density on the momentum transfer was obtained.With an increase in projectile density and length-diameter ratio,the energy transfer time between the projectile and targets is prolonged.The projectile decelerates slowly,resulting in a larger cratering depth.The energy consumed by the projectile in the excavation stage increased,resulting in lower mass-velocity of ejecta and momentum transfer coefficient.The numerical simulation results demonstrated that for different projectile/target combinations,the higher the wave impedance of the projectile,the higher the initial phase transition velocity and the smaller the mass of phase transition.The results can provide theoretical guidance for kinetic impactor design and material selection. 展开更多
关键词 Hypervelocity impact Energy partitioning impact melting Momentum transfer
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The impact of demographic dynamics on food consumption and its environmental outcomes:Evidence from China 被引量:2
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作者 Shaoting Li Xuan Chen +1 位作者 Yanjun Ren Thomas Glauben 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2024年第2期414-429,共16页
With increasing population and changing demographics,food consumption has experienced a significant transition in quantity and quality.However,a dearth of knowledge remains regarding its environmental impacts and how ... With increasing population and changing demographics,food consumption has experienced a significant transition in quantity and quality.However,a dearth of knowledge remains regarding its environmental impacts and how it responds to demographic dynamics,particularly in emerging economies like China.Using the two-stage Quadratic Almost Demand System(QUAIDS)model,this study empirically examines the impact of demographic dynamics on food consumption and its environmental outcomes based on the provincial data from 2000 to 2020 in China.Under various scenarios,according to changes in demographics,we extend our analysis to project the long-term trend of food consumption and its environmental impacts,including greenhouse gas(GHG)emissions,water footprint(WF),and land appropriation(LA).The results reveal that an increase in the proportion of senior people significantly decreases the consumption of grain and livestock meat and increases the consumption of poultry,egg,and aquatic products,particularly for urban residents.Moreover,an increase in the proportion of males in the population leads to higher consumption of poultry and aquatic products.Correspondingly,in the current scenario of an increased aging population and sex ratio,it is anticipated that GHG emissions,WF,and LA are likely to decrease by 1.37,2.52,and 3.56%,respectively.More importantly,in the scenario adhering to the standards of nutritional intake according to the Dietary Guidelines for Chinese Residents in 2022,GHG emissions,WF,and LA in urban areas would increase by 12.78,20.94,and 18.32%,respectively.Our findings suggest that changing demographics should be considered when designing policies to mitigate the diet-environment-health trilemma and achieve sustainable food consumption. 展开更多
关键词 demographic dynamics food consumption environmental impacts nutrition intakes
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Impact resistance performance and optimization of the sand-EPE composite cushion in rock sheds 被引量:2
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作者 YU Bingxin ZHOU Xiaojun +2 位作者 TANG Jianhui ZHANG Yujin ZHANG Yuefeng 《Journal of Mountain Science》 SCIE CSCD 2024年第2期676-689,共14页
Rock sheds are widely used to prevent rockfall disasters along roads in mountainous areas.To improve the capacity of rock sheds for resisting rockfall impact,a sand and expandable polyethylene(EPE)composite cushion wa... Rock sheds are widely used to prevent rockfall disasters along roads in mountainous areas.To improve the capacity of rock sheds for resisting rockfall impact,a sand and expandable polyethylene(EPE)composite cushion was proposed.A series of model experiments of rockfall impact on rock sheds were conducted,and the buried depth of the EPE foam board in the sand layer was considered.The impact load and dynamic response of the rock shed were investigated.The results show that the maximum impact load and dynamic response of the rock shed roof are all significantly less than those of the sand cushion.Moreover,as the distance between the EPE foam board and rock shed roof decreases,the maximum rockfall impact force and impact pressure gradually decrease,and the maximum displacement,acceleration and strain of the rock shed first decrease and then change little.In addition,the vibration acceleration and vertical displacement of the rock shed roof decrease from the centre to the edge and decrease faster along the longitudinal direction than that along the transverse direction.In conclusion,the buffering effect of the sand-EPE composite cushion is better than that of the pure sand cushion,and the EPE foam board at a depth of 1/3 the thickness of the sand layer is appropriate. 展开更多
关键词 ROCKFALL Rock shed impact Composite cushion Buffering effect Dynamic response
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Correction:Impact of Transition Metal Layer Vacancy on the Structure and Performance of P2 Type Layered Sodium Cathode Material 被引量:1
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作者 Orynbay Zhanadilov Sourav Baiju +7 位作者 Natalia Voronina Jun Ho Yu A-Yeon Kim Hun-Gi Jung Kyuwook Ihm Olivier Guillon Payam Kaghazchi Seung-Taek Myung 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第12期532-532,共1页
Following publication of the original article[1],the authors reported that the author Hun-Gi Jung should be affiliated as 3,4 and 5 instead of 4 and 5.The author’s name“A.-Yeon Kim”needed to be updated to“A-Yeon ... Following publication of the original article[1],the authors reported that the author Hun-Gi Jung should be affiliated as 3,4 and 5 instead of 4 and 5.The author’s name“A.-Yeon Kim”needed to be updated to“A-Yeon Kim”,removing the period.The correct author’s name and affiliation have been provided in this Correction.The original article[1]has been corrected. 展开更多
关键词 removing Transition impact
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基于MacBERT和R-Drop的地质命名实体识别 被引量:1
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作者 刘昕 徐洪珍 +1 位作者 刘爱华 邓德军 《郑州大学学报(工学版)》 CAS 北大核心 2024年第3期89-95,共7页
地质命名实体识别中常用的基于BERT预训练模型的深度学习方法是基于字的方法,没有利用词信息,且神经网络中的Dropout机制会导致训练阶段和推理阶段之间存在不一致性。针对该问题,提出了一种基于MacBERT和R-Drop的地质命名实体识别模型M... 地质命名实体识别中常用的基于BERT预训练模型的深度学习方法是基于字的方法,没有利用词信息,且神经网络中的Dropout机制会导致训练阶段和推理阶段之间存在不一致性。针对该问题,提出了一种基于MacBERT和R-Drop的地质命名实体识别模型MBCR。首先,通过MacBERT学习文本特征表示,充分利用字词信息;其次,运用BiGRU编码上下文特征,有效提取完整的语义信息;最后,采用CRF获取标签间的依赖关系,生成最优标签序列。此外,在训练过程中引入R-Drop,进一步提升模型的泛化能力。结果表明:与BiLSTM-CRF、BERTBiLSTM-CRF等模型相比,所提MBCR模型在NERdata数据集上的F1值提高了2.08百分点~4.62百分点,在Boson数据集上的F1值提高了1.26百分点~17.54百分点。 展开更多
关键词 命名实体识别 地质 MacBERT BiGRU R-drop
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A data-driven model of drop size prediction based on artificial neural networks using small-scale data sets 被引量:1
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作者 Bo Wang Han Zhou +3 位作者 Shan Jing Qiang Zheng Wenjie Lan Shaowei Li 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2024年第2期71-83,共13页
An artificial neural network(ANN)method is introduced to predict drop size in two kinds of pulsed columns with small-scale data sets.After training,the deviation between calculate and experimental results are 3.8%and ... An artificial neural network(ANN)method is introduced to predict drop size in two kinds of pulsed columns with small-scale data sets.After training,the deviation between calculate and experimental results are 3.8%and 9.3%,respectively.Through ANN model,the influence of interfacial tension and pulsation intensity on the droplet diameter has been developed.Droplet size gradually increases with the increase of interfacial tension,and decreases with the increase of pulse intensity.It can be seen that the accuracy of ANN model in predicting droplet size outside the training set range is reach the same level as the accuracy of correlation obtained based on experiments within this range.For two kinds of columns,the drop size prediction deviations of ANN model are 9.6%and 18.5%and the deviations in correlations are 11%and 15%. 展开更多
关键词 Artificial neural network drop size Solvent extraction Pulsed column Two-phase flow HYDRODYNAMICS
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Reinforcing effects of polypropylene on energy absorption and fracturing of cement-based tailings backfill under impact loading 被引量:1
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作者 Jiajian Li Shuai Cao Erol Yilmaz 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第4期650-664,共15页
Polypropylene(PP)fiber-reinforced cement-based tailings backfill(FRCTB)is a green compound material with superior crack resistance and has good prospects for application in underground mining.However,FRCTB exhibits su... Polypropylene(PP)fiber-reinforced cement-based tailings backfill(FRCTB)is a green compound material with superior crack resistance and has good prospects for application in underground mining.However,FRCTB exhibits susceptibility to dynamic events,such as impact ground pressure and blast vibrations.This paper investigates the energy and crack distribution behavior of FRCTB under dynamic impact,considering the height/diameter(H/D)effect.Split Hopkinson pressure bar,industrial computed tomography scan,and scanning electron microscopy(SEM)experiments were carried out on six types of FRCTB.Laboratory outcomes confirmed fiber aggregation at the bottom of specimens.When H/D was less than 0.8,the proportion of PP fibers distributed along theθangle direction of80°-90°increased.For the total energy,all samples presented similar energy absorption,reflectance,and transmittance.However,a rise in H/D may cause a rise in the energy absorption rate of FRCTB during the peak phase.A positive correlation existed between the average strain rate and absorbed energy per unit volume.The increase in H/D resulted in a decreased crack volume fraction of FRCTB.When the H/D was greater than or equal to 0.7,the maximum crack volume fraction of FRCTB was observed close to the incidence plane.Radial cracks were present only in the FRCTB with an H/D ratio of 0.5.Samples with H/D ratios of 0.5 and 0.6 showed similar distributions of weakly and heavily damaged areas.PP fibers can limit the emergence and expansion of cracks by influencing their path.SEM observations revealed considerable differences in the bonding strengths between fibers and the FRCTB.Fibers that adhered particularly well to the substrate were attracted together with the hydration products adhering to surfaces.These results show that FRCTB is promising as a sustainable and green backfill for determining the design properties of mining with backfill. 展开更多
关键词 cement-based tailings fiber-reinforced backfills FRACTURE energy absorption impact loading
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Impacts of Future Changes in Heavy Precipitation and Extreme Drought on the Economy over South China and Indochina 被引量:1
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作者 Bin TANG Wenting HU +4 位作者 Anmin DUAN Yimin LIU Wen BAO Yue XIN Xianyi YANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第6期1184-1200,I0022-I0034,共30页
Heavy precipitation and extreme drought have caused severe economic losses over South China and Indochina(INCSC)in recent decades.Given the areas with large gross domestic product(GDP)in the INCSC region are distribut... Heavy precipitation and extreme drought have caused severe economic losses over South China and Indochina(INCSC)in recent decades.Given the areas with large gross domestic product(GDP)in the INCSC region are distributed along the coastline and greatly affected by global warming,understanding the possible economic impacts induced by future changes in the maximum consecutive 5-day precipitation(RX5day)and the maximum consecutive dry days(CDD)is critical for adaptation planning in this region.Based on the latest data released by phase 6 of the Coupled Model Intercomparison Project(CMIP6),future projections of precipitation extremes with bias correction and their impacts on GDP over the INCSC region under the fossil-fueled development Shared Socioeconomic Pathway(SSP5-8.5)are investigated.Results indicate that RX5day will intensify robustly throughout the INCSC region,while CDD will lengthen in most regions under global warming.The changes in climate consistently dominate the effect on GDP over the INCSC region,rather than the change of GDP.If only considering the effect of climate change on GDP,the changes in precipitation extremes bring a larger impact on the economy in the future to the provinces of Hunan,Jiangxi,Fujian,Guangdong,and Hainan in South China,as well as the Malay Peninsula and southern Cambodia in Indochina.Thus,timely regional adaptation strategies are urgent for these regions.Moreover,from the sub-regional average viewpoint,over two thirds of CMIP6 models agree that maintaining a lower global warming level will reduce the economic impacts from heavy precipitation over the INCSC region. 展开更多
关键词 CMIP6 heavy precipitation extreme drought South China INDOCHINA economic impact
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Evolution of cavity size and energy conversion due to droplet impact on a water surface
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作者 Wan Xu Dekui Yuan +4 位作者 Hongguang Sun Tong Guo Fengze Zhao Huimin Ma Changgen Liu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2023年第10期261-269,共9页
The deformation characteristics of the cavity due to droplet impact on a water surface are experimentally investigated.Dimensional analysis shows that the characteristic values of time,depth,and horizontal diameter ca... The deformation characteristics of the cavity due to droplet impact on a water surface are experimentally investigated.Dimensional analysis shows that the characteristic values of time,depth,and horizontal diameter can be taken as 10^(-3)times the ratio of surface tension to the product of viscosity coefficient and gravitational acceleration,the maximum depth,and the maximum horizontal diameter,respectively.The evolutions of the dimensionless cavity sizes for different values of Weber number(We)coincide for 220<We<686.A partial-sphere model of cavity is established based on experimental observations.Energy models are then derived,and the energy conversions are calculated to identify the relationship between these conversions and cavity deformation.It is found that the kinetic energy model established under the hypothesis proposed by Leng is no longer applicable when the dimensionless time t^(*)<3.5,owing to deviations from the geometric model. 展开更多
关键词 droplet impact Cavity size Energy conversion
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Enhanced structural damage behavior of liquid-filled tank by reactive material projectile impact 被引量:1
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作者 Jianwen Xie Yuanfeng Zheng +4 位作者 Zhenyang Liu Chengzhe Liu Aoxin Liu Pengwan Chen Haifu Wang 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第1期211-229,共19页
A series of ballistic experiments were performed to investigate the damage behavior of high velocity reactive material projectiles(RMPs) impacting liquid-filled tanks,and the corresponding hydrodynamic ram(HRAM) was s... A series of ballistic experiments were performed to investigate the damage behavior of high velocity reactive material projectiles(RMPs) impacting liquid-filled tanks,and the corresponding hydrodynamic ram(HRAM) was studied in detail.PTFE/Al/W RMPs with steel-like and aluminum-like densities were prepared by a pressing/sintering process.The projectiles impacted a liquid-filled steel tank with front aluminum panel at approximately 1250 m/s.The corresponding cavity evolution characteristics and HRAM pressure were recorded by high-speed camera and pressure acquisition system,and further compared to those of steel and aluminum projectiles.Significantly different from the conical cavity formed by the inert metal projectile,the cavity formed by the RMP appeared as an ellipsoid with a conical front.The RMPs were demonstrated to enhance the radial growth velocity of cavity,the global HRAM pressure amplitude and the front panel damage,indicating the enhanced HRAM and structural damage behavior.Furthermore,combining the impact-induced fragmentation and deflagration characteristics,the cavity evolution of RMPs under the combined effect of kinetic energy impact and chemical energy release was analyzed.The mechanism of enhanced HRAM pressure induced by the RMPs was further revealed based on the theoretical model of the initial impact wave and the impulse analysis.Finally,the linear correlation between the deformation-thickness ratio and the non-dimensional impulse for the front panel was obtained and analyzed.It was determined that the enhanced near-field impulse induced by the RMPs was the dominant reason for the enhanced structural damage behavior. 展开更多
关键词 Reactive material projectile Hydrodynamic ram Enhanced structural damage Liquid-filled tank impact
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Drop weight impact analysis of GFRP tubes with hollow glass particle-filled matrix
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作者 Daniel Paul R.Velmurugan N.K.Gupta 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第11期1-9,共9页
Protecting occupants or payloads in crashes and blasts is of utmost importance in both moving and immobile structures.One way of achieving this is by using a sacrificial energy absorber.Composite tubes have been studi... Protecting occupants or payloads in crashes and blasts is of utmost importance in both moving and immobile structures.One way of achieving this is by using a sacrificial energy absorber.Composite tubes have been studied as potential energy absorbers due to their ability to fail progressively under axial compression.In this study,the energy absorption capability of these tubes is enhanced by adding hollow glass particles to the matrix.Drop-weight tests are performed on composite tubes,and a digital image correlation(DIC)-based technique is used to capture their load-displacement behaviour.This eliminates the use of electronic data acquisition systems,load cells,and accelerometers.The load-displacement curves of the tubes are obtained from the DIC-based technique and examined to understand their crushing behaviour.Although the mean crush load shows a drop,an increase in crush length is noticed.The specific energy absorbed by the tubes improves with an increase in GMB volume fraction.The addition of 0.1,0.2,0.3 and 0.4 vol fractions of GMB results in the specific energy absorption increasing by6.6%,14.7%,24%and 36.6%,respectively,compared to neat glass fibre-epoxy tubes.Visual examination of the tubes and comparison with tubes subject to quasi-static compression is also performed. 展开更多
关键词 Composite tubes Syntactic foam impact Axial compression Digital image correlation
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Impact response and energy absorption of metallic buffer with entangled wire mesh damper
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作者 Chao Zheng Jun Wu +1 位作者 Mangong Zhang Xin Xue 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第5期137-150,共14页
An innovative metallic buffer consisting of series-connected hat-shaped entangled wire mesh damper(EWMD)and parallel springs are proposed in this work to enhance the reliability of engineering equipment.The impact res... An innovative metallic buffer consisting of series-connected hat-shaped entangled wire mesh damper(EWMD)and parallel springs are proposed in this work to enhance the reliability of engineering equipment.The impact response and the energy dissipation mechanism of hat-shaped EWMD under different quasi-static compression deformations(2-7 mm)and impact heights(100-200 mm)are investigated using experimental and numerical methods.The results demonstrate distinct stages in the quasi-static mechanical characteristics of hat-shaped EWMD,including stiffness softening,negative stiffness,and stiffness hardening.The loss factor gradually increases with increasing compression deformation before entering the stiffness hardening stage.Under impact loads,the hat-shaped EWMD exhibits optimal impact energy absorption when it enters the negative stiffness stage(150 mm),resulting in the best impact isolation effect of metallic buffer.However,the impact energy absorption significantly decreases when hat-shaped EWMD enters the stiffness hardening stage.Interestingly,quasi-static compression analysis after experiencing different impact loads reveals the disappearance of the negative stiffness phenomenon.Moreover,with increasing impact loads,the stiffness hardening point progressively shifts to an earlier stage. 展开更多
关键词 Metallic buffer Hat-shaped EWMD drop impact Energy absorption characteristics Mechanical behavior
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Velocity equation for grenades while impacting on dry sand media
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作者 Martin Macko Xuan Son Bui +4 位作者 Kongsathit Phanthavong Duc Hung Pham Van Gion Do Van Minh Do Jiri Skala 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第5期168-173,共6页
This paper deals with the collision of sphere shape grenades with sand media.The central issue of the article is the establishing of an empirical velocity equation of the grenade while impacting on sand that is used t... This paper deals with the collision of sphere shape grenades with sand media.The central issue of the article is the establishing of an empirical velocity equation of the grenade while impacting on sand that is used to solve motion equations of the mechanical mechanism inside the impact grenade fuze.The paper focuses on impact velocities that are lower than 5 m s^(-1).An experiment was conducted to study the velocity of the grenade while impacting on dry sand.A high-speed camera video was used to capture the grenade positions.The grenade velocity in the impact process was generated from these video data.Some types of fitting curves are used to regress the velocity equation of the grenade while interacting with the sand media and the best-fitting model is chosen.The result shows the regression curve has a high correlation with the experiment data for grenade velocities below 5 m s^(-1).The received regression equation is useful for analyzing the working ability of the inertial mechanism inside the impact grenade or analyzing and choosing the appropriate parameters of each part in the inertial mechanism to meet the required characteristics of the mechanism. 展开更多
关键词 Dynamic response impact velocity impact grenade Low-velocity impact
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Instrumented oscillographic study on impact toughness of an axle steel DZ2 with different tempering temperatures
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作者 Shuo Liu Peng Zhang +6 位作者 Bin Wang Kaizhong Wang Zikuan Xu Fangzhong Hu Xin Bai Qiqiang Duan Zhefeng Zhang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第7期1590-1598,共9页
Compared with the conventional Charpy impact test method,the oscillographic impact test can help in the behavioral analysis of materials during the fracture process.In this study,the trade-off relationship between the... Compared with the conventional Charpy impact test method,the oscillographic impact test can help in the behavioral analysis of materials during the fracture process.In this study,the trade-off relationship between the strength and toughness of a DZ2 axle steel at various tempering temperatures and the cause of the improvement in impact toughness was evaluated.The tempering process dramatically influenced carbide precipitation behavior,which resulted in different aspect ratios of carbides.Impact toughness improved along with the rise in tempering temperature mainly due to the increase in energy required in impact crack propagation.The characteristics of the impact crack propagation process were studied through a comprehensive analysis of stress distribution,oscilloscopic impact statistics,fracture morphology,and carbide morphology.The poor impact toughness of low-tempering-temperature specimens was attributed to the increased number of stress concentration points caused by carbide morphology in the small plastic zone during the propagation process,which resulted in a mixed distribution of brittle and ductile fractures on the fracture surface. 展开更多
关键词 axle steel DZ2 tempering process impact toughness oscillographic impact test impact crack propagation carbides
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A novel approach to the dynamic response analysis of Euler-Bernoulli beams resting on a Winkler soil model and subjected to impact loads
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作者 Adolfo Foriero Filippo Santucci de Magistris Giovanni Fabbrocino 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第2期389-401,共13页
This work presents a novel approach to the dynamic response analysis of a Euler-Bernoulli beam resting on a Winkler soil model and subjected to an impact loading.The approach considers that damping has much less impor... This work presents a novel approach to the dynamic response analysis of a Euler-Bernoulli beam resting on a Winkler soil model and subjected to an impact loading.The approach considers that damping has much less importance in controlling the maximum response to impulsive loadings because the maximum response is reached in a very short time,before the damping forces can dissipate a significant portion of the energy input into the system.The development of two sine series solutions,relating to different types of impulsive loadings,one involving a single concentrated force and the other a distributed line load,are presented.This study revealed that when a simply supported Euler-Bernoulli beam,resting on a Winkler soil model,is subject to an impact load,the resulting vertical displacements,bending moments and shear forces produced along the span of the beam are considerably affected.In particular,the quantification of this effect is best observed,relative to the corresponding static solution,via an amplification factor.The computed impact amplification factors,for the sub-grade moduli used in this study,were in magnitude greater than 2,thus confirming the multiple-degree-of-freedom nature of the problem. 展开更多
关键词 beam-Winkler-soil model sub-grade moduli impact load impact distributed line load dynamic solution impact amplification factor
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