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Jet shape modification at LHC energies by JEWEL
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作者 万仁卓 丁雷 +3 位作者 桂熙 杨帆 李双 周代翠 《中国物理C:英文版》 SCIE CAS CSCD 2019年第5期107-113,共7页
Jet shape measurements are employed to explore the microscopic evolution mechanisms of parton-medium interaction in ultra-relativistic heavy-ion collisions. In this study, jet shape modifications are quantified in ter... Jet shape measurements are employed to explore the microscopic evolution mechanisms of parton-medium interaction in ultra-relativistic heavy-ion collisions. In this study, jet shape modifications are quantified in terms of the fragmentation function F(z), relative momentum pT^rel, density of charged particles p(r), jet angularity girth, jet momentum dispersion pT^disp,and LeS ub for proton-proton(pp) collisions at 0.9, 2.76. 5.02, 7,and 13 TeV, as well as for lead-lead collisions at 2.76 TeV and 5.02 TeV by JEWEL. A differential jet shape parameter Dgirth is proposed and studied at a smaller jet radius r < 0.3. The results indicate that the medium has the dominant effect on jet shape modification, which also has a weak dependence on the center-of-mass energy. Jet fragmentation is enhanced significantly at very low z < 0.02, and fragmented jet constituents are linearly spread to larger jet-radii for pT^rel < 1. The waveform attenuation phenomena is observed in pT^rel,girth, and Dgirth distributions. The results obtained for Dgirth from pp to Pb + Pb, where the wave-like distribution in pp collision is ahead of Pb + Pb collisions at small jetradii, indicates a strong medium effect. 展开更多
关键词 QUARK GLUON plasma JET QUENCHING JET suppression JET shape modifications JET structure
基于JET项目的文化外交软实力提升路径与对策 预览
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作者 林炜莉 《齐齐哈尔大学学报:哲学社会科学版》 2019年第1期181-185,共5页
JET项目是日本政府的一项国际交流事业,亦即日本政府聘用外国青年从事外语指导等工作的项目。该项目1992在中国年开始实施,对于中国提升文化软实力具有一定借鉴意义。目前JET项目国际化程度越来越高,给我国的文化外交提供了一个亚洲样... JET项目是日本政府的一项国际交流事业,亦即日本政府聘用外国青年从事外语指导等工作的项目。该项目1992在中国年开始实施,对于中国提升文化软实力具有一定借鉴意义。目前JET项目国际化程度越来越高,给我国的文化外交提供了一个亚洲样本。我国迫切需要建立民间国际交流品牌项目,以国际友好城市为依托加强国际人文交流;设立文化外交的民间统筹机构,从“一带一路”沿线国家招聘外语教学指导助手并加强和原在华工作外国人的联系与交流,破解“一带一路”倡议推行中遇到的文化“软阻力”,向世界展现中国发展的全球责任与博大胸襟。 展开更多
关键词 JET项目 国际交流 文化外交 软实力
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Ventilatory effect of normal frequency jet ventilation in non-intubated anesthesia in the treatment of the palmar hyperhidrosis
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作者 Shu-Rong Li Qing-Hua Wu +1 位作者 Chun-Lan Lin Yao-Hua Yu 《海南医科大学学报(英文版)》 2019年第7期25-29,共5页
Objective: To evaluate the ventilatory effect of normal frequency jet ventilation via Wei jet nasal airway in non-intubated anesthesia in the treatment of the palmar hyperhidrosis (PH). Methods: 62 patients with PH un... Objective: To evaluate the ventilatory effect of normal frequency jet ventilation via Wei jet nasal airway in non-intubated anesthesia in the treatment of the palmar hyperhidrosis (PH). Methods: 62 patients with PH undergoing video-assisted thoracoscopic sympathectomy, aged 18~35 years, ASA I-II, were randomized into two groups: intubated group (group T) and normal-frequency jet ventilation group (group J). After induction tracheal tubes were inserted in Group T and Wei nasal airway were inserted in group J. The heart rate(HR),saturation pulse oxygen (SPO2), mean artery pressure (MAP) and end-tidal carbon dioxide partial pressure (PETCO2) were recorded at following time points: before induction (T0),1 min after induction (T1), 1 min after tube insertion/ intubation (T2), when trocars were inserted and carbon dioxide was inflated (T3), during lung recruitment maneuver and the chest closure (T4), the moment of extubation (T5), 15 min after extubation (T6). Blood samples were taken from left radial artery for blood gas analysis to monitor carbon dioxide partial pressure, arterial oxygen partial pressure, PH ,the BE at T0, T4, T6.The duration of anesthesia, awaking time ,the dosage of the propofol and the remifentanil, the intraoperative and postoperative adverse events were recorded. Results: Compared with group T, the HR and MAP were more stable in group J. The awaking time in the group J were significantly shorter than those in group T (P<0.05), the dosage of the remifentanil in group J was significantly less than that in group T (P<0.05), The incidences of throat discomfort, nausea and vomiting were lower than those in group T (P<0.05). Conclusion: Normal-frequency jet ventilation via Wei jet nasal airway in non-intubated anesthesia in the treatment of the (PH)is feasible, which can reduce stress response and make hemodynamics stable without the complications of tracheal intubation. 展开更多
关键词 Non-intubation SUPRAGLOTTIC Normal-frequency JET ventilation Wei JET NASAL AIRWAY THORACIC SYMPATHECTOMY
台风“莫兰蒂”登陆前后引起的浙江沿海地区强降水过程分析 预览
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作者 董加斌 黄新晴 《应用海洋学学报》 CSCD 北大核心 2019年第2期198-205,共8页
用实况降水、雷达反射率、欧洲中心(ECMWF)全球模式细网格及0.5°×0.5°分辨率ERA-Interim再分析等资料,对2016年15日发生在浙江省沿海地区的强降水过程进行分析和诊断,结果表明:该过程是由14号台风“莫兰蒂”的外围螺旋... 用实况降水、雷达反射率、欧洲中心(ECMWF)全球模式细网格及0.5°×0.5°分辨率ERA-Interim再分析等资料,对2016年15日发生在浙江省沿海地区的强降水过程进行分析和诊断,结果表明:该过程是由14号台风“莫兰蒂”的外围螺旋雨带产生的;15日在浙江东部沿海地区有充沛的水汽,源源不断的水汽输送和明显的不稳定层结条件;在边界层辐合线、山脉地形、边界层急流头部三者共同作用下,该区域形成强烈的边界层辐合上升运动,触发了对流;对流层高层200hPa高空急流右后侧和气流发散区叠加,提供了强的高空水平辐散,有利于低层辐合上升的维持和发展,最终导致浙江沿海地区发生强降水。对比分析发现模式预报的边界层东南偏东急流及边界层辐合线均明显比实况弱,这可能是各大数值预报中心对这次过程的预报都明显偏小的主要原因,说明边界层东南偏东急流及边界层辐合线对于强降水具有重要作用。 展开更多
关键词 海洋气象学 台风 强降水 急流 边界层辐合线 数值模式检验
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碳化硅-铝射流侵彻新型反应装甲的仿真研究
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作者 朱越亭 马铁华 +1 位作者 沈大伟 张红艳 《兵器材料科学与工程》 CAS CSCD 北大核心 2019年第3期95-99,共5页
为研究碳化硅-铝(SiC-Al)射流对新型反应装甲的侵彻性能,运用AUTODYN软件仿真计算,分析不同参数的SiC-Al射流成型规律以及对新型反应装甲的侵彻效果。结果表明:锥角、装药高度对SiC-Al射流成型影响较大,锥角80°时成型效果最好,装... 为研究碳化硅-铝(SiC-Al)射流对新型反应装甲的侵彻性能,运用AUTODYN软件仿真计算,分析不同参数的SiC-Al射流成型规律以及对新型反应装甲的侵彻效果。结果表明:锥角、装药高度对SiC-Al射流成型影响较大,锥角80°时成型效果最好,装药高度为1.3D和1.5D时射流头部较稳定;射流头部速度随锥角、壁厚的增大而减小,随装药高度的增大而增大;射流侵彻反应装甲时,侵彻效果随药型罩壁厚的增大而增强,随炸高的减小而减弱,可实现对新型反应装甲的穿而不爆。 展开更多
关键词 碳化硅-铝 射流 反应装甲 穿而不爆
截顶M形药型罩形成射流的数值模拟及侵彻性能试验 预览
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作者 安文同 高永宏 +2 位作者 孙建军 周杰 尹楚藩 《火炸药学报》 CAS CSCD 北大核心 2019年第4期410-414,共5页
为了提高聚能射流的侵彻性能,结合超高速射流理论设计了一种截顶M形药型罩,运用有限元分析软件ANSYS/LS-DYNA对该药型罩形成射流的过程和射流侵彻靶板的过程进行数值模拟研究;对该药型罩和锥角药型罩形成射流的性能进行比较,并采用静破... 为了提高聚能射流的侵彻性能,结合超高速射流理论设计了一种截顶M形药型罩,运用有限元分析软件ANSYS/LS-DYNA对该药型罩形成射流的过程和射流侵彻靶板的过程进行数值模拟研究;对该药型罩和锥角药型罩形成射流的性能进行比较,并采用静破甲实验进行验证。结果表明,截顶药型罩顶部在爆轰压力作用下先形成内外环形射流,内外环形射流汇聚后形成二级环形射流,二级环形射流汇聚后形成聚能射流头部;截顶M形药型罩形成的射流,头部速度更高,射流头部速度比锥角药型罩提高4.2%,射流速度梯度变大;截顶M形药型罩形成的射流侵彻深度比锥角药型罩提高36.06%,且侵彻形貌较均匀;数值模拟结果与试验结果误差小于5%,具有良好的一致性。 展开更多
关键词 爆炸力学 截顶M形药型罩 聚能装药 破甲战斗部 射流 侵彻性能
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基于FLUENT的压电式无针注射器喷嘴射流分析 预览
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作者 张铁民 李晟华 +1 位作者 梁莉 梅园 《振动.测试与诊断》 EI CSCD 北大核心 2019年第2期273-280,440,441共10页
为研究压电式无针注射器的喷嘴结构对其射流形态、平均喷射速度和平均湍流强度的影响,首先,基于粘性不可压缩流体纳维-斯托克斯方程,利用计算流体动力学软件Fluent的Realizable k-ε湍流模型和流场体积函数多相流模型,对四种结构的喷嘴... 为研究压电式无针注射器的喷嘴结构对其射流形态、平均喷射速度和平均湍流强度的影响,首先,基于粘性不可压缩流体纳维-斯托克斯方程,利用计算流体动力学软件Fluent的Realizable k-ε湍流模型和流场体积函数多相流模型,对四种结构的喷嘴高压自由射流进行数值模拟,结果显示,锥柱形结构的喷嘴能得到可控性较好的对称射流;其次,利用正交试验法对锥柱形结构喷嘴的锥形收缩角和中部圆柱长度进行设计仿真分析,以得到上述结构参数及其交互作用对喷嘴的平均喷射速度和平均湍流强度的影响;最后,利用SPSS软件对仿真结果进行分析。结果表明,中部圆柱长度对喷嘴的平均喷射速度和平均湍流强度具有显著影响,锥形收缩角对前者无显著影响,而对后者具有显著影响,中部圆柱长度和锥形收缩角的交互作用对前者和后者均无显著影响。综合考虑,当锥形收缩角为30°、中部圆柱长度为0.2mm时,锥柱形喷嘴可得到最佳射流特性,此时出口平均速度可达6.56m/s,湍流强度均值为1.04%。该研究可为压电式无针注射器的喷嘴设计提供参考。 展开更多
关键词 无针注射 喷嘴 压电效应 射流
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Cavitation vortex dynamics of unsteady sheet/cloud cavitating flows with shock wave using different vortex identification methods 预览
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作者 Chang-chang Wang Ying Liu +3 位作者 Jie Chen Fu-yi Zhang Biao Huang Guo-yu Wang 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第3期475-494,共20页
Cavitation is a complex multiphase flow phenomenon with an abrupt transient phase change between the liquid and the vapor, including multiscale vortical motions. The transient cavitation dynamics is closely associated... Cavitation is a complex multiphase flow phenomenon with an abrupt transient phase change between the liquid and the vapor, including multiscale vortical motions. The transient cavitation dynamics is closely associated with the evolution of the cavitation vortex structures. The present paper investigates the cavitation vortex dynamics using different vortex identification methods, including the vorticity method, the Q criterion method, the Omega method (Ω), the method and the Rortex method. The Q criterion is an eigenvalue-based criterion, and in the Ω method, the parameter is normalized, is independent of the threshold value and in most conditions Ω= 0.52 . The Rortex method is based on an eigenvector-based criterion. Numerical simulations are conducted using the implemented compressible cavitation solver in the open source software OpenFOAM for the sheet/cloud cavitating flows around a NACA66 (mod) hydrofoil fixed at a = 6°,= 1.25 and Re = 7.96 × 10^5 . The flow is characterized by the alternate interactions of the re-entrant flow and the collapse induced shock wave. Results include the vapor structures and the vortex dynamics in the unsteady sheet/cloud cavitating flows, with emphasis on the vortex structures in thecavitation region, the cavity interface, the cavity closure, the cavity wakes, and the foil wakes with the shedding cavity. The comparisons of the various methods, including that the vorticity method, the Q criterion method, the Ω method, the λ2 method and the Rortex method, show the performances of different methods in identifying the cavitation vortex structures. Generally, during the attached cavity growth stage, the Q criteria can well predict the vortex structures in the cavitation region and at the foil trailing edge in the pure liquid region, while with the Ω method and the Rortex method, the vortex structures outside the attached cavity and on the foil pressure side can also be predicted. The λ2 method can well predict the vortex structures in the cavity closure region. During the re 展开更多
关键词 CAVITATION VORTEX dynamics VORTEX identification sheet/cloud cavitating flow RE-ENTRANT jet shock wave OPENFOAM
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Key structure in laminar-turbulent transition of boundary layer with streaky structures 预览
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作者 Joe Yoshikawa Yu Nishio +1 位作者 Seiichiro Izawa Yu Fukunishi 《力学快报:英文版》 CAS CSCD 2019年第1期32-35,I0005共5页
A numerical simulation is performed to find out a key vortical structure in the laminar-turbulent transition. A low-speed streak is generated inside a laminar boundary layer using an isolated cuboid roughness, aimed a... A numerical simulation is performed to find out a key vortical structure in the laminar-turbulent transition. A low-speed streak is generated inside a laminar boundary layer using an isolated cuboid roughness, aimed at providing an environment unstable to outer disturbances. Then, a short duration jet is issued into the boundary layer. When the jet velocity is low, some vortices appear in the boundary layer, but the transition of the boundary layer does not take place. However, when the jet velocity exceeds a certain threshold, two vortices newly appear above the elongated legs of a V-shaped vortex and only one of them is stretched and survives. After that, vortices are generated one after another around the survived one. By comparing the decayed and the survived vortices, it is found that the difference in their heights is the key characteristic which leads to the transition. 展开更多
关键词 Turbulent ONSET KEY vortical STRUCTURE Laminar-turbulent transition Boundary layer Streaky STRUCTURES Short DURATION jet Numerical simulation
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Molten steel level stability in continuous casting slab mold under electromagnetic stirring 预览
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作者 WEN Hongquan WU Cunyou ZHOU Yueming 《宝钢技术研究:英文版》 CAS 2019年第1期25-31,共7页
Fluctuation of molten steel level in continuous casting process is a critical issue.The analytic function for the liquid steel surface stability index( F ) of the continuous casting slab mold under the action of elect... Fluctuation of molten steel level in continuous casting process is a critical issue.The analytic function for the liquid steel surface stability index( F ) of the continuous casting slab mold under the action of electromagnetic stirring was derived.The effects on the F value of the electromagnetic field,casting mold,submerged entry nozzle,and casting speed were observed,and the stability of the process parameters of a practical continuous casting system was evaluated.The main results generated are as follows:① Based on the free flow jet theory,a formula is established for the level stability index of continuous casting slab mold under electromagnetic stirring.② According to the results of calculation,the various parameters in decreasing order of the magnitude of their influence are magnetic flux density,nozzle submersion depth,casting speed,slab width,stirring current frequency,and nozzle side-hole inclination angle.③ For practical continuous casting with a slab thickness of 230 mm,the calculated F values are between 3 and 5 for different matches between slab width and casting speed,but the parameter optimization space is much larger for wider slab widths and lower casting speeds. 展开更多
关键词 LEVEL STABILITY free flow jet electromagnetic STIRRING F -index continuous casting mold
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超临界二氧化碳粒子射流破岩性能分析 预览
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作者 杜玉昆 陈晓红 +5 位作者 王瑞和 岳伟民 杜强 白殿刚 郝国亮 周艳 《中国石油大学学报:自然科学版》 EI CAS CSCD 北大核心 2019年第2期85-90,共6页
由于页岩和致密砂岩等非常规储层岩石的破岩门限压力大,为充分发挥超临界二氧化碳在开发非常规资源方面的技术优势,提出引入粒子后形成超临界二氧化碳粒子射流,提高射流的破岩效率。在优化超临界二氧化碳射流破岩实验流程的基础上,研制... 由于页岩和致密砂岩等非常规储层岩石的破岩门限压力大,为充分发挥超临界二氧化碳在开发非常规资源方面的技术优势,提出引入粒子后形成超临界二氧化碳粒子射流,提高射流的破岩效率。在优化超临界二氧化碳射流破岩实验流程的基础上,研制超临界二氧化碳粒子射流破岩实验装置,分析超临界二氧化碳粒子射流的破岩性能。结果表明:相对于纯超临界二氧化碳射流,加入石英砂30 s后超临界二氧化碳粒子射流的破岩性能得到大幅度增强,破岩体积提高了66.67%;超临界二氧化碳粒子射流的破岩性能随着喷嘴直径和喷距的增大先增强后减弱;本试验条件下最优喷嘴直径为3 mm、喷距为6 mm,粒径为0.3~0.5 mm;压力和温度越高,射流的破岩性能越强,但增强的趋势逐渐变缓。 展开更多
关键词 超临界二氧化碳 粒子 射流 破岩
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双排孔顺-逆射流组合方式对气膜冷却的影响
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作者 李广超 高志阳 +2 位作者 张魏 张国臣 寇志海 《推进技术》 EI CAS CSCD 北大核心 2019年第3期643-652,共10页
为了挖掘逆向射流气膜冷却潜力,数值模拟研究了顺向射流和逆向射流不同组合方式的双排孔气膜冷却叠加特性。吹风比变化为0.3~1.4。结果表明,展向平均气膜冷却效率数值模拟结果与实验值偏差小于9%。逆向射流在气膜孔出口产生的回流涡强... 为了挖掘逆向射流气膜冷却潜力,数值模拟研究了顺向射流和逆向射流不同组合方式的双排孔气膜冷却叠加特性。吹风比变化为0.3~1.4。结果表明,展向平均气膜冷却效率数值模拟结果与实验值偏差小于9%。逆向射流在气膜孔出口产生的回流涡强化了气膜展向扩散,吹风比越大,强化效果越明显。吹风比为1.4时,与顺向射流+顺向射流组合结构的叠加区气膜冷却效率相比,上游顺向射流+下游逆向射流组合结构展向平均气膜冷却效率提高17%~233%,面平均气膜冷却效率提高64%;逆向射流+逆向射流组合结构展向平均气膜冷却效率提高0~410%,面平均气膜冷却效率提高62%;上游逆向射流+下游顺向射流组合展向平均气膜冷却效率提高16%~70%,面平均气膜冷却效率提高44%。 展开更多
关键词 气膜冷却 射流 逆向射流 数值模拟
Generalized equation for calculating rock cutting efficiency by pulsed water jets 预览
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作者 Andrey Polyakov Aleksandr Zhabin +1 位作者 Eugene Averin Aleksey Polyakov 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第4期867-873,共7页
One of the promising methods for rock cutting technology is the use of high-speed water jets.In order to improve the cutting capacity of water jets without increasing the hydraulic power of equipment,pulsed water jets... One of the promising methods for rock cutting technology is the use of high-speed water jets.In order to improve the cutting capacity of water jets without increasing the hydraulic power of equipment,pulsed water jets are basically used to increase the rock cutting efficiency.However,there are no mature recommendations for selection of rational parameters,and the relationship between indicators of rock cutting efficiency and parameters of pulsed water jet is still not established.In this context,we aimed at developing a generalized equation for calculating rock cutting efficiency,in which all the major parameters in consideration of rock cutting process are included.Then,a calibration of the rational parameters of rock cutting by pulsed water jets was conducted.The results are likely helpful for increasing productivity and reducing energy consumption. 展开更多
关键词 PULSED WATER jets Rock cutting WATER JET technology Generalized equation DEPTH of CUT
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射流侵彻混凝土最大孔径工程计算 预览
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作者 曾令清 冯成良 +2 位作者 曾燚 邱鹏鹰 刘俞平 《兵器装备工程学报》 CAS 北大核心 2019年第A01期66-68,共3页
射流微元侵彻时,考虑其能量全部用于侵彻扩孔,获得了射流侵彻混凝土最大孔径的工程计算方法,与有关试验结果进行了比对,吻合较好。
关键词 射流 侵彻 混凝土 孔径
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Expulsive force in the development of C02 sequestration:application of SC-C02 jet in oil and gas extraction
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作者 Haizhu WANG Gensheng LI Zhonghou SHEN 《能源前沿:英文版》 CSCD 2019年第1期1-8,共8页
With the rapid development of global economy,an increasing amount of attention has been paid to the emission of greenhouse gases,especially CO2.In recent years,dominated by the governments around the world,several sig... With the rapid development of global economy,an increasing amount of attention has been paid to the emission of greenhouse gases,especially CO2.In recent years,dominated by the governments around the world,several significant projects of CO2 sequestration have been conducted.However,due to the huge investment and poor economic effects,the sustainability of those projects is not satisfactory.Supercritical CO2(SC-CO2)has prominent advantages in well drilling,fracturing,displacement,storage,plug and scale removal within tubing and casing,which could bring considerable economic benefits along with CO2 sequestration.In this paper,based on physicochemical properties of SC-CO2 fluid,a detailed analysis of technical advantages of SC-CO2 applied in oil and gas development is illustrated.Furthermore,the implementation processes of SC-CO2 are also proposed.For the first time,a recycling process is presented in which oil and gas are extracted and the CO2 generated could be restored underground,thus an integrated technology system is formed.Considering the recent interests in the development of enhancing hydrocarbon recoveries and CO2 sequestration,this approach provides a promising techni?que that can achieve these two goals simultaneously. 展开更多
关键词 CO2 SEQUESTRATION SC-CO2 JET WELL DRILLING FRACTURING oil and gas
Analysis on the Influence Factors of Directional Controlled Blasting Assisted by Water Jet 预览
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作者 SU Dengfeng 《地质资源与工程:英文版》 2019年第2期45-56,共12页
Directional expansion of blast-induced crack is always the common purpose for directional controlled blasting. As it has been demonstrated that slot which located at the side of blasthole can function as a guidance fo... Directional expansion of blast-induced crack is always the common purpose for directional controlled blasting. As it has been demonstrated that slot which located at the side of blasthole can function as a guidance for blast energy, let the stress concentration at the direction of water jet slot. Therefore, it is meaningful to investigate the influence factors of directional controlled blasting with water jet assistance. In this paper, the influence on the guiding characteristics of the water jet slot during the propagation of blast-induced crack by the change of length-width of slot was simulated by ANSYS/LS-DYNA. The results indicate that if the distance from blasthole exceeds the limit, the influence on the guiding characteristics by the change length-width of the slot will get smaller and smaller, and when the width of water jet slot remains the same, the stress shows a monotonic increasing trend with the increase of the length of water jet slot, and the stress reaches its maximum value when the length-width of water jet slot is 0.075m×0.0070m. Moreover, based on stress wave theory and rock fracture theory, the influential mechanism for both the law of transmission of stress wave and of crack propagation by natural fracture and water jet slot were analyzed. The criteria for blast-induced crack propagation were established. 展开更多
关键词 Blast-induced CRACK water JET SLOT numerical simulation influence FACTORS
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基于油泥射流冲击技术数值模拟 预览
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作者 张晓慧 朱根民 《机械工程师》 2019年第5期40-42,共3页
针对地下原油储库长期运营之后出现的油泥沉积问题,研究了油泥密度对射流冲击效果的影响。使用ANSYS16.0软件实现地下储库的喷射全流场数值模拟,采用单因素敏感分析法对不同油泥密度下流场进行对比。数值分析结果表明:油泥密度主要影响... 针对地下原油储库长期运营之后出现的油泥沉积问题,研究了油泥密度对射流冲击效果的影响。使用ANSYS16.0软件实现地下储库的喷射全流场数值模拟,采用单因素敏感分析法对不同油泥密度下流场进行对比。数值分析结果表明:油泥密度主要影响射流流场中后段的混合情况,对射流初始段的流场混合情况影响较小;流场的混合程度随着油泥密度的减小逐渐增大;油泥流速的增加率与油泥密度成反比;油泥流速的衰减率与油泥密度成正比。 展开更多
关键词 地下水封洞库 原油沉积 射流 数值模拟
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Recent Advances in Hole Making of FRP/Metal Stacks:A Review 预览
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作者 CHEN Yan YANG Haojun +2 位作者 XU Jiuhua FU Yucan YAN Chaoren 《南京航空航天大学学报:英文版》 EI CSCD 2019年第3期361-375,共15页
Weight reduction is a key driving force for materials development in aerospace industry,which leads to extensive usage of lightweight structural materials such as fiber reinforced polymer(FRP),titanium alloy,aluminum ... Weight reduction is a key driving force for materials development in aerospace industry,which leads to extensive usage of lightweight structural materials such as fiber reinforced polymer(FRP),titanium alloy,aluminum alloy,etc.Hole making is indispensable to assembling these lightweight components by riveted or bolted joints.However,hole making of FRP / metal stacks is always the most challenging task due to differences of material properties between FRP and metals.A comprehensive literature review on hole making of FRP/metal stacks in the last decade is given with a focus on four main aspects including drilling operation,drilling damages and machining parameter optimization,tool performance and wear,and developments in hole making technology.Finally,in order to ensure the precise and efficient hole making of FRP/metal stacks,an idea of low frequency vibration assisted drilling(LFVAD)FRP/metal stacks based on material removal characteristics is put forward by fully exploiting the unique advantages of LFVAD technology. 展开更多
关键词 fiber reinforced polymer (FRP)/metal STACKS DRILLING MACHINING quality tool wear helical MILLING vibration assisted DRILLING abrasive water jet MACHINING
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史上首张黑洞照片的科学与技术
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作者 吴学兵 《科学通报》 EI CAS CSCD 北大核心 2019年第20期2082-2086,共5页
黑洞是爱因斯坦广义相对论预言的产物,也是宇宙中最神秘的天体.2019年4月10日,事件视界望远镜(Event Horizon Telescope,EHT)国际合作团队公布了利用全球的8个毫米波望远镜组成的干涉阵以约20微角秒的分辨率拍摄的首张黑洞照片,直接测... 黑洞是爱因斯坦广义相对论预言的产物,也是宇宙中最神秘的天体.2019年4月10日,事件视界望远镜(Event Horizon Telescope,EHT)国际合作团队公布了利用全球的8个毫米波望远镜组成的干涉阵以约20微角秒的分辨率拍摄的首张黑洞照片,直接测量了射电星系M87中心黑洞的阴影和黑洞周围光环的大小,得到了M87中心黑洞的质量为65亿太阳质量(1太阳质量=1.9891×10^30kg),引起举世轰动. 展开更多
关键词 中心黑洞 科学与技术 照片 爱因斯坦广义相对论 太阳质量 事件视界 国际合作 射电星系
A new solution to enhance cuttings transport in mining drilling by using pulse jet mill technique
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作者 LIU YongSheng GAO DeLi +3 位作者 WEI Zheng BALACHANDRAN Balakumar WANG ZhenQuan TAN LeiChuan 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2019年第5期875-884,共10页
In horizontal drilling, the cuttings bed is frequently formed to result in severe problems such as backing pressure, binding of bottom hole assembly(BHA) and even sticking of tool. Practice and research show that the ... In horizontal drilling, the cuttings bed is frequently formed to result in severe problems such as backing pressure, binding of bottom hole assembly(BHA) and even sticking of tool. Practice and research show that the smaller particle size is, the more favorable to carry out from bottom of hole in extended reach well or horizontal well. This paper presented a new solution to enhance cuttings transport in mining drilling through a new type of bit called pulsed mill bit(PMB) by using pulse jet mill technique. It provides a promising solution to enhance the efficiencies of rock breaking and cuttings carrying for pulsed jet,sucking cuttings to decrease the chip hold down effect, and reducing cuttings’ diameter to eliminate cuttings bed. The design was supported by the calculation models of Helmholtz resonator natural frequency, optimal drilling fluid flow rate of resonator,drilling fluid flow velocity in forward jet channel, critical impact velocity of cuttings and minimum length of the accelerating cavity. Meanwhile, factors affecting optimal drilling fluid flow rate, critical impact velocity of cuttings and minimum length of accelerating cavity were investigated. Case study showed a good consistency between the calculation results and the related theories. It is concluded that optimal drilling fluid flow rate increases with the increase of inlet and outlet cavity’s diameter, and decreases with the increase of the diameter of the resonant cavity. Critical impact velocity of cuttings increases with the energy conversion factor(β) and ROP, while decreasing with the final size of the cuttings(dt). This effect is obvious when β<0.2, ROP<3.048 mh-1 and dt<0.3 mm. Minimum length of the accelerating cavity decreases with the increase of the resonator’s natural frequency and separation coefficient(α) of drilling fluid flow rate. This study provides a promising solution to remove cuttings bed in horizontal well. 展开更多
关键词 PULSE jet MILL TECHNIQUE CUTTINGS bed HELMHOLTZ RESONATOR optimal flow rate critical impact velocity
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