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Effects of weight on bit on torsional stick-slip vibration of oilwell drill string
Liping Tang,Xiaohua Zhu,Xudong Qian,Changshuai Shi 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10
The stick-slip phenomenon is a type of dysfunction detrimental to the drilling operation. Field application shows that stick-slip phenomenon is inclined to appear when using a large Weight on bit (WOB). In this paper, effects of the WOB on the stick-slip vibration are investigated. Based on a lumped torsional pendulum model of the drilling system, equation of motion of the drill bit is obtained. By using parameters commonly used in field applications, the bit dynamics are analyzed and the stick-slip vibrations are discussed. During the stick-slip motions, the negative damping effect occurs in the transition from the stick phase to the slip phase. With the increasing WOB, the bit behavior may change from the stable motion to the stick-slip vibration once the WOB reaches the critical value. In case of stickslip vibration, the phase trajectory ultimately converges to a limit cycle which represents periodical bit motion. With increases in the WOB, the limit cycle enlarges. For cases without stick-slip vibrations, the drill bit vibrates damply and finally converges to a state of uniform motion. The results presented in this paper can be applied to interpret some of the field phenomena related to WOB.
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Chao Tang,Jianmei Chen,Yuxin Li,Xinchao Liu,Lili Zhang,Fangfang Wang,Jia Hu,Xudong Cao,Tao Jiang 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.2
Three new pyridine-cored alkyl-substituted carbazole derivatives of 2,6-bis(2,7-dimethyl-9H-carbazol-9-yl)pyridine(2,7-MeCzPy), 2,6-bis(3,6-dimethyl-9H-carbazol-9-yl) pyridine (3,6-MeCzPy) and 2,6-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)pyridine (3,6-tBuCzPy) were synthesized by means of connecting methyl or tert-butyl substituents on the3,6 or 2,7 positions of carbazole with pyridine ring as the core. The influence of different alkyl and linkages modeon the thermal, photophysical, electrochemical properties and devices electrolumiescent (EL) performances of thecompounds were comprehensively studied. In solution-processed blue or green phosphorescent organic light-emittingdiodes (PHOLEDs) with bis[2-(4,6-difluorophenyl)-pyridinato-N,C2] picolinate iridium(III) (FIrpic) or fac-tris(2-phenylpyridine)iridium (Ir(ppy)3) as phosphorescent dopants, EL performances follow the same sequence of 2,7-MeCzPy> 3,6-tBuCzPy > 3,6-MeCzPy, the trend is consistent with the value of triplet energies (ET). Devices hosted by2,7-MeCzPy achieving the best EL performance, exhibited maxima 13.6 cd A−1 and 7.0 lm W−1 for current efficiency(CE) and power efficiency (PE) in blue PHOLEDs, maxima 26.2 cd A−1 and 16.2 lm W−1 for CE and PE in greenPHOLEDs.
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JinYu Lu,XuDong Qiao,Jie Liao,Yi Tang 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.4
Numerous experimental and finite element studies have shown that steel plate shear walls with slits have several beneficial characteristics, such as good ductility and excellent energy dissipation capacity, which make them a feasible lateral load resisting and energy dissipation system for high-rise buildings in high seismic regions. The width of the flexural links between slits has a significant effect on the mechanical behavior and hysteretic performance of steel plate shear walls with slits. This paper presented two kinds of steel plate shear walls with non-uniform spacing slits (SPWNS) and investigated their performance under low-cycle loading based on tests and finite element software. The study mainly focused on the ultimate bearing capacity, the lateral stiffness, the energy dissipation capacity and the ductility of SPWNS. The results from numerical analysis and test study were compared with each other. The ultimate bearing capacity and the lateral stiffness of traditional steel plate shear walls with uniform spacing slits (SPWUS) were similar to that of SPWNS. In contrast, the ductility and the energy dissipation capacity of SPWUS were much higher.
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Screening and Cloning of RAPD Markers from the W Chromosome of Silkworm, Bombyx mori L.
Chunxia Zhang,Qin Yao,Qinggang Xu,Xudong Tang,Keping Chen 한국잠사학회 2004 International Journal of Industrial Entomology Vol.8 No.2
Silkworms sex determination drew high attention from researchers. Sex chromosomes on the silkworm are of ZW type for females and ZZ type for males. Chromosome W plays an important role in sex determination. Although several molecular linkage maps have been constructed for silkworm, very few markers are discovered on the W chromosome. In order to look for molecular markers and to further locate the Fem gene on chromosome W, we used genomic DNA from both female and male larvae of a silkworm strain named 937 as PCR templates for RAPD amplification with 200 arbitrary 10-mer primers. The amplification results showed three female-specific bands, namely OPG-07496, OPC-151,660 and OPE-181,279. Further verification, however, revealed no band from OPG-07 and OPC-15 in either sex in the strain 798, but OPE-18 provided female-specific band in the strains Suluan7 and C108, and absent in both males and strain 798. This indicates that the bands from OPG-07496 and OPC-151,660 are probably female-specific in strain 937, and the band from OPE-18 was probably amplified from a common segment shared by most strains. The genomic DNAs from OPG-07 and OPC-15 were cloned and sequenced. Sequence analysis showed that the DNAs from OPG-07 and OPC-15 have high identities with the retrotransposable elements, and DNA from OPC-15 contains a portion of sequence which probably encodes an eukaryotic translation initiation factor 4E binding protein (eIF4EBP).
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Screening and Cloning of RAPD Markers from the W Chromosome of Silkworm, Bombyx mori L.
Chen, Keping,Zhang, Chunxia,Yao, Qin,Xu, Qinggang,Tang, Xudong Korean Society of Sericultural Science 2004 International Journal of Industrial Entomology Vol.8 No.2
Silkworms sex determination drew high attention from researchers. Sex chromosomes on the silkworm are of ZW type for females and ZZ type for males. Chromosome W plays an important role in sex determination. Although several molecular linkage maps have been constructed for silkworm, very few markers are discovered on the W chromosome. In order to look for molecular markers and to further locate the Fern gene on chromosome W, we used genomic DNA from both female and male larvae of a silkworm strain named 937 as PCR templates for RAPD amplification with 200 arbitrary 10-mer primers. The amplification results showed three female-specific bands, namely ${OPG-07_496}, {OPC-15_1,660} and {OPE-18_1,279}$. Further verification, however, revealed no band from OPG-07 and OPC-15 in either sex in the strain 798, but OPE-18 provided female-specific band in the strains Suluan7 and C108, and absent in both males and strain 798. This indicates that the bands from ${OPG-07_496} and {OPC-15_1,660}$ are probably female-specific in strain 937, and the band from OPE-18 was probably amplified from a common segment shared by most strains. The genomic DNAs from OPG-07 and OPC-15 were cloned and sequenced. Sequence analysis showed that the DNAs from OPG-07 and OPC-15 have high identities with the retrotransposable elements, and DNA from OPC-15 contains a portion of sequence which probably encodes an eukaryotic translation initiation factor 4E binding protein (eIF4EBP).
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