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Dynamic behavior analysis of push-the-bit rotary steerable bottom hole assembly
Zhi-chuan Guan,Heng Wang,Yu-cai Shi,Wei-qing Chen,Guo-shan Zhao,Jian-yun Wang,Guang-qiang Cao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.4
Rotary steerable drilling technology is currently an advanced technology in the field of drilling engineering. A good understanding of dynamic behavior of rotary steerable system will benefit the drilling progress. Aimed at push-the-bit type of rotary steerable tool, finite element method was employed to model the rotary steerable bottom hole assembly (RSBHA) and establish the motion equation. Contact interaction between drill string and wellbore wall was analyzed and taken as the constraint condition in solving RSBHA motion equation. Force applied by steering pads was as the external force acting at the pads node. Then RSBHA motion state and bit lateral force were obtained by using Newmark method to solve the motion equation. A case was given and effects of influencing factors were analyzed. The results show that stick-slip phenomenon occurs under 60 r/min rotary speed condition and disappears when rotary speed rises to 90 r/min. Fully developed backward whirl comes into being at the near-bit stabilizer when rotary speed increases to 120 r/min. High weight on bit intensifies bit torsional vibration while larger pads’ steering force decreases the bit torsional vibration. Upper stabilizer plays a part in weakening RSBHA backward whirl under high rotary speed condition but reduces the inclination force. Time average of bit lateral force is mainly determined by pads’ steering force. Based on the results, corresponding suggestions were proposed to make the RSBHA be better used in the field applications.
Zhi Cao,Yunkai Huang,Baocheng Guo,Jianning Dong,Fei Peng 한국자기학회 2020 Journal of Magnetics Vol.25 No.2
This paper applies two different analytical methods, i.e., the perturbation method and superposition method, to calculate the magnetic flux density distribution and the magnetic force of the active magnetic bearing (AMB) with the rotor eccentricity. These two methods are thoroughly analyzed, compared and validated by the finite element model (FEM). The perturbation method is theoretically complex while the superposition method is intuitive. The valid range of the superposition method is larger than the perturbation method. However, the superposition method requires longer computation time. The main contribution of this paper is assessing the effectiveness of two analytical methods for predicting the AMB performance with the rotor eccentricity and giving a comprehensive guideline for engineers to choose the proper analytical method to design AMB.
DNMT3a rs1550117 Polymorphism Association with Increased Risk of Helicobacter pylori Infection
Cao, Xue-Yuan,Jia, Zhi-Fang,Cao, Dong-Hui,Kong, Fei,Jin, Mei-Shan,Suo, Jian,Jiang, Jing Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.10
Background: DNA methyltransferase-3a (DNMT3a) plays significant roles in embryogenesis and the generation of aberrant methylation in carcinogenesis. This study aimed to investigate associations between single nucleotide polymorphisms (SNPs) of the DNMT3a gene and risk of Helicobacter pylori infection, gastric atrophy and gastric cancer. Methods: The subjects comprised 447 patients with gastric cancer; 111 individuals with gastric atrophy and 961 healthy controls. Two SNPs (rs1550117 and rs13420827) of the DNMT3a gene were genotyped by Taqman assay. DNMT3a expression was analyzed in cancer tissues from 89 patients by tissue microarray technique. Odds ratio (ORs) and 95% confidence intervals were calculated by multivariate logistic regression. Results: Among healthy controls, risk of H.pylori infection was significantly higher in subjects with the rs1550117 AA genotype, compared to those with GG/AG genotypes of DNMT3a [OR=2.08, (95%CI: 1.02-4.32)]. However, no significant correlation was found between the two SNPs and risk of developing gastric atrophy or gastric cancer. In addition, no increase in DNMT3a expression was observed in the gastric cancer with H.pylori infection. Conclusions: This study revealed that DNMT3a rs1550117 polymorphism is significantly associated with an increased risk of H. pylori infection, but did not support any evidence for contributions of DNMT3a rs1550117 and rs13420827 to either gastric atrophy or gastric cancer. The biological roles of DNMT3a polymorphisms require further investigation.
Duan-Jian Tao,Yan Dong,Zhi-Jun Cao,Feng-Feng Chen,Xiang-Shu Chen,Kuan Huang 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.41 No.-
A series of sulfonic functionalized ionic liquids (SFILs) with different acidity were designed and preparedfor the synthesis of terpene esters (e.g. geranyl acetate). The effect of acidity of SFILs on their performancewas investigated systematically. It is found that tuning the acidity of SFILs to an appropriate value resultsin not only high conversion of geraniol but also superior selectivity of geranyl acetate. The SFILs can beeasily separated from products byfiltration under room temperature, thus showing good reusability. Furthermore, the kinetics for SFILs in the esterification of geraniol were determined as the basis for futureprocess design.
Wei Zhao,Zhi-Gang Yuan,Yue-hong Shen,Yufan Cao,Yimin Wei,Pengcheng Xu,Wei Jian 한국전자통신연구원 2015 ETRI Journal Vol.37 No.4
This paper deals with the problem of blind source separation (BSS), where observed signals are a mixture of delayed sources. In reference to a previous work, when the delay time is small such that the first-order Taylor approximation holds, delayed observations are transformed into an instantaneous mixture of original sources and their derivatives, for which an extended second-order blind identification (SOBI) approach is used to recover sources. Inspired by the results of this previous work, we propose to generalize its first-order Taylor approximation to suit higher-order approximations in the case of a large delay time based on a similar version of its extended SOBI. Compared to SOBI and its extended version for a first-order Taylor approximation, our method is more efficient in terms of separation quality when the delay time is large. Simulation results verify the performance of our approach under different time delays and signal-to-noise ratio conditions, respectively.
Multiscale cooling technology for data centers
Xing Zhang,Zhen Li,Zhi Guang He,Tao Ding,Jian Feng Han,Hanwen Cao 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.4
Huge amount of heat is generated in data centers and it needs to be removed to outdoors through cooling equipment. In recent years the energy consumption and heat dissipation density of data centers increases sharply. The cooling technology of data centers has become a hot research focus. This article orderly introduces three types of cooling technologies in different scales and some relevant experiments are included. Besides, the energy consumption of each cooling technology is analyzed.
Tian, Shu-Bo,Yu, Jian-Chun,Kang, Wei-Ming,Ma, Zhi-Qiang,Ye, Xin,Cao, Zhan-Jiang,Yan, Chao Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.15
Our aim was to investigate the value of combined detection of serum carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 19-9, CA 242 and CA 50 in diagnosis and assessment of prognosis in consecutive gastric cancer patients. Clinical data including preoperative serum CEA, CA 19-9, CA 242, and CA 50 values and information on clinical pathological factors were collected and analyzed retrospectively. Univariate and multivariate survival analyses were used to explore the relationship between tumor markers and survival. Positive rates of tumor markers CEA, CA 19-9, CA 242 and CA 50 in the diagnosis of gastric cancer were 17.7, 17.1, 20.4 and 13.8%, respectively, and the positive rate for all four markers combined was 36.6%. Patients with elevated preoperative serum concentrations of CEA, CA 19-9, CA 242 and CA 50, had late clinical tumor stage and significantly poorer overall survival. Five-year survival rates in patients with elevated CEA, CA 19-9, CA 242 and CA 50 were 28.1, 25.8, 27.0 and 24.1%, respectively, compared with 55.0, 55.4, 56.4 and 54.5% in patients with these markers at normal levels (p<0.01). In multivariate Cox proportional hazards analyses, an elevated CA 242 level was determined to be an independent prognostic marker in gastric cancer patients. Combined detection of four tumor markers increased the positive rate for gastric cancer diagnosis. CA 242 showed higher diagnostic value and CA 50 showed lower diagnostic value. In resectable gastric carcinoma, preoperative CA 242 level was associated with disease stage, and was found to be a significant independent prognostic marker in gastric cancer patients.
Xue-Zhou Wang,Cun-Zhi Liu,Li-Qiong Wang,Zhi-Cheng Qu,Ying Cao,Shi-Yan Yan,Jing-Wen Yang,Jian-Feng Tu 한국한의학연구원 2024 Integrative Medicine Research Vol.13 No.1
Background: The integration of acupuncture with intramuscular injection of diclofenac sodium can expedite the onset of analgesia in treating acute renal colic caused by urolithiasis. However, it remains unclear whether acupuncture can accelerate pain relief constantly until complete remission. This study aimed to explore the extent to which acupuncture can expedite the onset time of response or complete pain relief in treating acute renal colic, and the predictive value of patient characteristics for treatment efficacy. Methods: This secondary analysis utilized data from a prior randomized controlled trial. Eighty patients with acute renal colic were randomly assigned 1:1 to the acupuncture group or the sham acupuncture group. After intramuscular injection of diclofenac sodium, acupuncture or sham acupuncture was delivered to patients. The outcomes included time to response (at least a 50 % reduction in pain) and complete pain relief. Between-group comparison under the 2 events was estimated by Kaplan-Meier methodology. Subgroup analysis was performed utilizing the Cox proportional hazards model. Results: The median response time and complete pain relief time in the acupuncture group were lower than those in the sham acupuncture group (5 vs 30 min, Log Rank P < 0.001; 20 min vs not observed, Log Rank P < 0.001, respectively). Hazard Ratios (HRs) for response across all subgroups favored the acupuncture group. All HRs for complete pain relief favored acupuncture, expect large stone and moderate pain at baseline. No interaction was found in either event. Conclusion: Acupuncture can accelerate the response time and complete pain relief time for patients with acute renal colic, with the efficacy universally. Trial registration: This study has been registered at Chinese Clinical Trial Registry: ChiCTR1900025202.