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Effects of projectile parameters on the momentum transfer and projectile melting during hypervelocity impact

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Defence Technology（防务技术） 2024年第2期32卷 89-103页

作者： wenjin liu Qingming Zhang Renrong Long Zizheng Gong Ren Jiankang Xin Hu Siyuan Ren Qiang Wu Guangming Song State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China Beijing Institute of Spacecraft Environment Engineering China Academy of Space TechnologyBeijing100094China

The effects of projectile/target impedance matching and projectile shape on energy,momentum transfer and projectile melting during collisions are investigated by numerical *** comparing the computation results with the experimental results,the correctness of the calculation and the statistical method of momentum transfer coefficient is *** shapes of aluminum,copper and heavy tungsten alloy projectiles striking aluminum,basalt,and pumice target for impacts up to 10 km/s are *** influence mechanism of the shape of the projectile and projectile/target density on the momentum transfer was *** an increase in projectile density and length-diameter ratio,the energy transfer time between the projectile and targets is *** projectile decelerates slowly,resulting in a larger cratering *** energy consumed by the projectile in the excavation stage increased,resulting in lower mass-velocity of ejecta and momentum transfer *** 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 *** results can provide theoretical guidance for kinetic impactor design and material selection.

关键词： Hypervelocity impact Energy partitioning Impact melting Momentum transfer

Orbital pacing and secular evolution of lake-level changes reconstructed by sedimentary noise modeling during the Early Jurassic icehouses-(super)greenhouses

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Science China Earth Sciences 2024年第1期67卷 252-267页

作者： Meng LI Xin LI Stephen P.HESSELBO Mingjie LI wenjin liu Wei WU Jienan PAN Ruizhen GAO School of Resources and Environment Henan Polytechnic UniversityJiaozuo 454000China Camborne School of Mines and Environment and Sustainability Institute University of ExeterPenryn TR109FEUnited Kingdom Qinghai No.105 Coal Geological Exploration Team Xining 810000China

Lake-level changes can significantly affect paleoenvironmental evolution,resource occurrence,terrestrial carbon budget,and biodiversity in continental *** is one of the most critical factors controlling lake-level *** of the Early Jurassic has been evidenced by oscillating icehouses to(super)greenhouses with interrupted intermittent extreme climatic events(hyperthermal and cooling),e.g.,the Toarcian oceanic anoxic event(~183 Ma)and the late Pliensbachian cooling event(~185 Ma).Lake-level evolution and hydrologic cycling on Earth’s surface during the Early Jurassic icehouses-to-(super)greenhouses are thus far poorly understood due to a lack of continuous high-resolution nonmarine *** we present a super-long nonmarine lake level record for this pivotal interval from the early Pliensbachian to Toarcian by sedimentary noise modeling,and construct a 16.7-Myr-long astronomical time scale(174.2 Ma to 190.9 Ma)based on cyclostratigraphy analysis of rock color datasets(CIE b*)of the Qaidam *** results document lake-level oscillations on a 5-to 10-million-year(Myr)scale which shows a pronounced correlation with long-term climate variation and extreme climatic events,and 1-to 2.5-Myr-scale lake-level changes that are prominently paced by the 2.4-Myr long-eccentricity forcing and the 1.2-Myr obliquity *** the Pliensbachian Stage,the 1.2-Myr-scale lake-level changes are in phase with the coeval sealevel *** forced growth and decay of the ephemeral or permanent ice sheets in polar regions are interpreted to control the synchronous ups-and-downs of continental lake level and global sea ***,during the Toarcian ice-free greenhouses to(super)greenhouses,the 1.2-Myr-scale lake-level variations show an anti-phase relationship with global sea level,indicating a‘seesaw’interaction between continental reservoirs(lakes and groundwater)and global *** 2.4-Myr longeccentricity cycles mainly regulate variation

关键词： Milankovitch cycles Orbital forcing Sedimentary noise model Lake level Continental basins

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典型石油热加工技术发展现状及展望

化工进展 2024年第7期43卷 3534-3550页

作者：刘文津张玉明李家州张炜陈哲文中国石油大学(北京)机械与储运工程学院重质油全国重点实验室北京102249

石油热加工技术是在热量作用下使石油及其产物发生热裂化和缩合反应生成不同产品,涉及石油炼制与化工生产的绝大多数加工过程,属于“热化学反应工程”分支之一。随着第三次能源转型持续推进,石油炼制行业正面临“油转化”的重大生产结... 详细信息

石油热加工技术是在热量作用下使石油及其产物发生热裂化和缩合反应生成不同产品,涉及石油炼制与化工生产的绝大多数加工过程,属于“热化学反应工程”分支之一。随着第三次能源转型持续推进,石油炼制行业正面临“油转化”的重大生产结构调整,促使以热化学反应为核心的石油热加工技术不断发展,包括以重油轻质化为主要目标的减黏裂化、延迟焦化、重油流化热裂化技术以及以低碳烯烃为主要目标的蒸汽裂解技术。为了更为高效地将石油转化为低碳烯烃,将热化学反应进一步与催化反应耦合,发展出含催化热载体的轻油催化热裂解和重油催化热裂解两类热化学-催化耦合热加工技术。本文对上述六种典型石油热加工技术的演变历程、技术特点、发展现状与前景进行了纵向梳理,并从不同维度对其进行横向对比分析。对比发现,热加工中热载体循环再生能够有效解决工艺过程焦炭处理问题,且能与催化反应相耦合,使得重油流化热裂化、轻油催化热裂解和重油催化热裂解等热加工技术在原料适应性、产物灵活性、环保性方面具有突出优势。此外,将电气化技术进一步与蒸汽裂解及以外的其他热加工技术相结合,可有效提升石油热加工领域未来的整体环保性和节能性。

关键词：石油热加工重油轻质化低碳烯烃热化学-催化耦合热加工

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In-situ TiC Reinforced Composite Coating Produced by Powder Feeding Laser Cladding

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Journal of Materials Science & Technology 2006年第4期22卷 519-525页

作者： Sen YANG wenjin liu Minlin ZHONG Department of Materials Science and Engineering Inner Mongolia University of Technology Hohhot 010062 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China

A Ni-base alloy composite coating reinforced with TiC particles of various shapes and sizes on medium carbon steel substrate was produced by multilayer laser cladding. The chemical compositions, microstructures and surface morphology of the cladded layer were analyzed using energy dispersive X-ray spectroscopy （EDX）, scanning electron microscope （SEM）, and X-ray diffractometry （XRD）. The experimental results showed that an excellent metallurgical bonding between the coating and the substrate was obtained. The microstructure of the coating was mainly composed of γ-Ni dendrites, a small amount of CrB, Ni3B, M23C6 and dispersed TiC particles. Much more and larger TiC particles formed in the overlapping zone, which led to a slightly higher microhardness of this zone. The maximum microhardness of the coating was about HV0.21200. The effects of the laser processing parameters on the microstructures and properties of coating were also investigated.

关键词： Laser cladding In-situ synthesized Powder feeding TiC particle

多焦点经颅直流电刺激激活运动皮层对骑行耐力表现的影响

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体育科学 2024年第3期44卷 41-50,88页

作者：梁志强王亚杰刘稳进于经伦亓朔吕娇娇刘宇上海体育大学“运动健身科技”省部共建教育部重点实验室上海200438 上海体育大学运动健康学院上海200438 山东体育学院运动与健康学院山东济南250102

目的:以前额叶皮层和运动皮层为目标脑区,在健康人群中探索多焦点经颅直流电刺激(transcranial direct current stimulation,tDCS)同时刺激多脑区对骑行耐力表现的影响。方法:受试者在功率自行车上进行递增负荷耐力运动,期间采用功能性... 详细信息

目的:以前额叶皮层和运动皮层为目标脑区,在健康人群中探索多焦点经颅直流电刺激(transcranial direct current stimulation,tDCS)同时刺激多脑区对骑行耐力表现的影响。方法:受试者在功率自行车上进行递增负荷耐力运动,期间采用功能性近红外光谱脑成像系统监测目标皮层运动终止时的血流动力学表现,通过分析皮层激活与运动时间的相关性确定目标脑区。其后采用多焦点tDCS针对性刺激目标脑区,分析和比较刺激前后最后阶段运动表现和下肢肌肉均方根振幅(root mean square amplitude,RMS),评估刺激干预对骑行耐力表现的影响。结果:1)前额叶皮层和运动皮层在运动终止时大面积激活,其中运动皮层FC1h、FC2h、C1h和C2h的激活与运动时间显著负相关。2)相比刺激前,运动中的心率在多焦点tDCS刺激后显著降低;相比Sham组,多焦点tDCS刺激显著提高运动的做功量和骑行转速。3)推进期,相比刺激前,股直肌、股四头肌内侧、股四头肌外侧和胫骨前肌的RMS在多焦点tDCS刺激后显著降低;相比Sham组,多焦点tDCS组股二头肌RMS在刺激后呈现低的激活水平。提拉期,相比刺激前,股二头肌RMS在多焦点tDCS刺激后显著降低;相比Sham组,多焦点tDCS组股四头肌内侧的RMS在刺激后呈现高的激活水平,腓肠肌外侧RMS在刺激后呈现低的激活水平。结论:多焦点tDCS特异性激活运动皮层提高了骑行耐力表现和机体对运动的适应性,多焦点tDCS可能是增强耐力运动表现的一种有效手段。

关键词：功能性近红外光谱脑成像经颅直流电刺激骑行皮层激活耐力运动表现

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ThERF1 regulates its target genes via binding to a novel cis-acting element in response to salt stress

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Journal of Integrative Plant Biology 2015年第10期57卷 838-847页

作者： liuqiang Wang Chao Wang Liping Qin wenjin liu Yucheng Wang Key Laboratory of Biogeography and Bioresource in Arid Land Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences State Key Laboratory of Tree Genetics and Breeding (Northeast Forestry University)

Ethylene responsive factors (ERFs) are plant-specific transcription factors that are involved in a variety of biological processes. We previously demonstrated that an ERF gene from Tamarix hispida, ThERF1, encodes a protein binding to GCC-box and DRE motifs and negatively modulates abiotic stress tolerance. In the present study, microarray analysis was performed to study the genes regulated by ThERF1 on a genomic scale. There were 154 and 307 genes (respectively representing 134 and 260 unique genes) significantly up- and downregulated by ThERF1 under salt stress conditions, respectively. A novel motif, named TTG, was identified to be recognized by ThERF1, which commonly presents in the promoters of ThERF1-targeted genes. The TTG motif is also bound by other ERFs of a different subfamily from T. hispida and Arabidopsis, indicating that it is commonly recognized by ERF proteins. The binding affinities of ERFs to the TTG motif are significantly induced by salt stress. The TTG motif is more enriched than the GCC-box and DRE motifs in the promoters of ThERF1-targeted genes. Taken together, these studies suggested that the TTG motif plays an important role in the gene expression regulated by ERFs in response to salt stress.

关键词： Abiotic stress ChIP ethylene response factor Tamarix hispida yeast one-hybrid

清宫正骨手法联合针刺治疗神经根型颈椎病急性期(气滞血瘀证)的疗效观察

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中国中医急症 2024年第8期33卷 1420-1423页

作者：刘文金陈美君林凤华广东省湛江市第二中医医院广东湛江524011 广州中医药大学广东广州510405 广东省江门市五邑中医院广东江门529099 暨南大学广东广州510632 广东省江门市工贸职业技术学校广东江门529000

目的观察针刺基础上联合清宫正骨手法治疗神经根型颈椎病(CSR)(气滞血瘀证)患者的疗效、症状改善及对炎症因子水平的影响。方法将CSR患者60例按照随机数字表法分为两组各30例,对照组采用针刺治疗,治疗组在针刺基础上采用清宫正骨手法,... 详细信息

目的观察针刺基础上联合清宫正骨手法治疗神经根型颈椎病(CSR)(气滞血瘀证)患者的疗效、症状改善及对炎症因子水平的影响。方法将CSR患者60例按照随机数字表法分为两组各30例,对照组采用针刺治疗,治疗组在针刺基础上采用清宫正骨手法,共治疗2周。观察两组症状、疼痛及颈部功能障碍评分的差异性,比较临床效果和炎症因子水平。结果治疗组总有效率为93.33%,高于对照组的73.33%(P<0.05)。与对照组相比较,治疗组治疗后症状、疼痛、颈椎功能障碍评分以及炎症因子水平明显更低(P<0.05)。结论清宫正骨手法联合针刺治疗CSR疗效良好,可有效减轻患者疼痛,改善患者的颈椎功能,缓解临床症状,降低机体炎症水平,且安全性良好。

关键词：神经根型颈椎病清宫正骨手法针刺气滞血瘀证急性期

A slope-based decoupling algorithm to simultaneously control dual deformable mirrors in a woofer–tweeter adaptive optics system

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Chinese Physics B 2018年第7期27卷 248-256页

作者： Tao Cheng wenjin liu Boqing Pang Ping Yang Bing Xu Key Laboratory on Adaptive Optics Chinese Academy of Sciences Chengdu 610209 China University of Chinese Academy of Sciences Beijing 100049 China Institute of Optics and Electronics Chinese Academy of Sciences Chengdu 610209 China

We propose a slope-based decoupling algorithm to simultaneously control the dual deformable mirrors （DMs） in a woofer-tweeter adaptive optics system. This algorithm can directly use the woofer＇s response matrix measured from a Shack-Hartmann wave-front sensor to construct a slope-based orthogonal basis, and then selectively distribute the large- amplitude low-order aberration to woofer DM and the remaining aberration to tweeter DM through the slope-based orthogonal basis. At the same moment, in order to avoid the two DMs generating opposite compensation, a constraint matrix used to reset tweeter control vector is convenient to be calculated with the slope-based orthogonal basis. Numeral simulation demonstrates that this algorithm has a good performance to control the adaptive optics system with dual DMs simultaneously. Compared with the typical decoupling algorithm, this algorithm can take full use of the compensation ability of woofer DM and release the stroke of tweeter DM to compensate high-order aberration. More importantly, it does not need to measure the accurate shape of tweeter＇s influence function and keeps better performance of restraining the coupling error with the continuous-dynamic aberration.

关键词： dual deformable mirrors decoupling algorithm adaptive optics

NAD(P)H inspired CO_(2) reduction and beyond

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Science China Chemistry 2024年第4期67卷 1044-1046页

作者： wenjin Dong Jian liu Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of SciencesShandong Energy InstituteQingdao 266101China

The catalytic reduction of carbon dioxide to fuels and valueadded chemicals under mild conditions is recognized as a promising strategy to alleviate the energy *** the Calvin cycle of natural photosynthesis,CO_(2)reduction is achieved using cofactor nicotinamide adenine dinucleotide phosphate(NADPH)as a practical catalyst,shedding light on the biomimetic metal-free reduction of CO_(2).

关键词： dioxide dinucleotide catalyst