Results 41 to 50 of about 287 (108)
Shiyou jixie, 2015 通过地质钻探对赋藏岩心进行取样是最为直观有效的水合物勘探方法。钻头钻进过程中往往会产生较高的温升，天然气水合物赋藏岩层对外界条件又具有非常高的敏感性，其周围温度和压力条件的改变会使水合物分解。为此，建立有限元模型并对钻头破岩过程进行仿真模拟，重点研究了取样钻头、水合物赋藏岩层以及岩心样品的温度分布和变化情况。研究结果表明，取样过程中温升较高的区域主要集中在井底，最高温升在井底呈散点状分布；钻头钻进时切削齿前端面尖点首先与岩层接触产生摩擦热，热量由尖点向内部传递导致温度梯度；钻速越高，钻头转速越快 ...
段小龙 +4 more
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[Influence of cavity design on quality of margin and marginal adaptation and microleakage of all-ceramic CAD/CAM inlays]. [PDF]
Beijing Da Xue Xue Bao Yi Xue Ban, 2023 Zhao SM, Wang XY.
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Shiyou jixie, 2015 为提高页岩气钻井效率、减少钻头泥包，根据现场常用PDC钻头建立三维流域模型，将岩屑模拟为从井底面射入流场的球状颗粒，用拉格朗日粒子追踪法描述固相，将钻头体DPM边界条件设置为捕获，以岩屑颗粒捕获率作为反映泥包可能性的评价参数，结合井底流场结构特点，模拟分析了岩屑输运与黏附规律。数值模拟结果表明，井底岩屑输运时沿程存在碰撞与反弹的不规则三维运动，这导致部分岩屑黏附到钻头体表面；对于不同尺寸的岩屑颗粒，各刀翼和排屑槽的岩屑颗粒捕获率Ra呈类似的变化规律，当岩屑粒径为10 mm时Ra最大，当粒径小于1 mm时，
陈修平 +5 more
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Jixie chuandong, 2008 Aimed at a kind of rotary cutting machine,the machining process of involute gear chamfering is kinematically analyzed,and the moving locus equations of cutting edge are deduced.The chamfering process is dynamically simulated.The analyzing results provide
胡昌军, 钱瑞明
doaj
Effects of 3 kinds of processing techniques on the fitness of metal clasp. [PDF]
Zhong Nan Da Xue Xue Bao Yi Xue Ban, 2021 Yin X +5 more
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Clinical application and research progress of digital complete denture. [PDF]
Hua Xi Kou Qiang Yi Xue Za Zhi, 2021 Zhou YS, Sun YC, Wang Y.
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Simultaneous implantation and tooth preparation technology guided by 3D-printed guide. [PDF]
Hua Xi Kou Qiang Yi Xue Za Zhi, 2023 Hu N +6 more
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[Initial exploration of the relationship between homeostatic occlusion and long-term dental implant stability]. [PDF]
Hua Xi Kou Qiang Yi Xue Za ZhiChen J, Wu L.
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[Relationship between fluid shear stress in alveolar bone under orthodontic forces and bone remodeling rate]. [PDF]
Hua Xi Kou Qiang Yi Xue Za ZhiWu B +6 more
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