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Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to further improve the drilling performance of polycrystalline diamond composite (PDC) bit in deep hard formation and restrain the occurrence of the viscous sliding phenomenon, a circular saw-shaped imitation tooth based on the bionic similarity principle and saw-shaped tooth structure was proposed based on the mole claw toe as the prototype. Based on elastic-plastic mechanics and finite element nonlinear dynamics theory, a simulation model of rock breaking of cutter and bit was established. The rock-breaking process of the serrated tooth and circular serrated tooth was compared, and the whole drilling process of the two kinds of serrated bit was compared. The results show that the circular arc sawing teeth are mainly used to break rock by plow and shovel, which can concentrate the load, reach the yield limit of rock more easily, and make the rock more easily broken by tensile stress. The cutting force is reduced by 15.8% compared with the sawing teeth, and the efficiency is higher. The bit with a circular saw bionic PDC teeth can break more rock, improve the footage significantly, and suffer less torque, which can effectively solve the viscous sliding of the bit. The research results have important reference values for the design of high-performance drill bits in China. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Clinical Healthcare is the property of Chinese Journal of Clinical Healthcare and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The structure of polycrystalline diamond compact(PDC) cutter is an important factor affecting the performance of the drill bit. The serrated PDC cutter has good performance but less research, and lacks relevant theoretical support. Therefore, based on elastoplastic mechanics and Drucker-Prager criterion, the finite element model of cutter and rock was constructed, and the rock breaking and temperature field of serrated PDC and conventional PDC cutter were compared. The results show that the serrated PDC effectively and significantly improved the rock breaking efficiency by shearing and ploughing. The mean cutting force of serrated PDC was about 20% lower than that of conventional PDC, and the fluctuation was obviously smaller. When the back rake angle became larger, the cutting force increases, and the specific energy of rock breaking increased first, then decreases and increased again. There was an optimal back rake angle of 10° ~ 15°. With the increase of cutting depth, the cutting force increases, and the specific energy of rock breaking decreases first and then increases. There was a critical cutting depth of 1. 5 ~ 2 mm. As the number of serrations increases, the cutting force and rock breaking specific energy of the cutter increase first and then decrease, and the three serrations were the best. The results of temperature field research show that the serrated PDC has a larger heat dissipation area and better thermal stability than the conventional PDC cutter, and there is a law between working parameters and temperature changes. The research depth reveals the rock breaking characteristics and temperature field of the serrated PDC cutter, which has important guiding significance for PDC cutter optimization and high-performance bit tooth arrangement. [ABSTRACT FROM AUTHOR]

In order to solve ordinary impregnated diamond bit (normal bit), low efficiency of rock fragmentation, drilling is not stable, not wear-resisting, and not according to choose a suitable form of broken rock stratum, combined with the bionic nonplanar structural design principle and the bottom of the tooth and a new type of polycrystalline diamond compact(PDC) bit lip surface, a bit bottom lip surface sensor installed on the lithology identification was proposed. The intelligent bionic PDC bit (intelligent bit) can be selected to break rock with appropriate shape. Machine learning was used to classify rock properties based on field drilling data. Based on the established cutting model and rock failure criteria, the rock breaking process of the intelligent bit and the common bit is numerically simulated and compared. The results show that the weighted KNN (K-nearest neighbor)algorithm based on machine learning can well avoid the problem of sample overlap and accurately classify the rock properties. Its training model can be provided to the sensor for lithology identification. When sandstone is broken, the bottom lip with PDC teeth and the bionic bottom lip of the intelligent bit are adjusted by the sensor to keep the same height of rock breaking. Compared with the ordinary bit, the rock breaking specific energy and cutting force are significantly smaller, indicating that its efficiency is higher and the cutting is more stable. When granite is broken, the intelligent bit will be adjusted by the sensor to lower the bottom lip with PDC teeth to break rock, and its rock breaking efficiency is significantly higher than that of the ordinary bit, but also more stable. The research results are of great significance to the intelligent development of oil drilling equipment. [ABSTRACT FROM AUTHOR]

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Clinical Healthcare is the property of Chinese Journal of Clinical Healthcare and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Clinical Healthcare is the property of Chinese Journal of Clinical Healthcare and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Clinical Healthcare is the property of Chinese Journal of Clinical Healthcare and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Clinical Healthcare is the property of Chinese Journal of Clinical Healthcare and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Clinical Healthcare is the property of Chinese Journal of Clinical Healthcare and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Pharmaceutial Care & Research is the property of Editorial Board of Pharmaceutial Care & Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

目的 探讨贝那普利与氨氯地平联合口服对老年高血压患者血压变异性及血浆一氧化氮与内皮素水平的影响。方法 42例老年高血压患者(高血压组),同时选取血压正常老年人30例为对照组。高血压组给予贝那普利与氨氯地平联合口服降压治疗。高血压组治疗前、治疗第8周、治疗第16周与对照组治疗前均监测24 h动态血压、检测血浆一氧化氮与内皮素。结果 治疗前,高血压组收缩压变异性(SBPV)、舒张压变异性(DBPV)均高于对照组(P均<0.05);治疗第8周,高血压组24 h SBPV、白昼SBPV、夜间SBPV、24 h DBPV、夜间DBPV较治疗前降低(P均<0.05);治疗第16周,高血压组24 h SBPV、白昼SBPV、24 h DBPV、白昼DBPV较治疗前降低(P均<0.05)。治疗前,高血压组血浆一氧化氮水平低于对照组,内皮素水平高于对照组(P均<0.01);治疗后,高血压组血浆一氧化氮水平进行性升高(P均<0.01),内皮素水平进行性降低(P均<0.0)。结论 贝那普利与氨氯地平联合口服能降低老年高血压患者的血压变异性、改善血管内皮功能。 [ABSTRACT FROM AUTHOR]