The mechanical behavior of the test string in deep wells is generally relatively complex as a result of the high temperature and high pressure,severe dogleg and buckling effects,which in some circumstances can even le...The mechanical behavior of the test string in deep wells is generally relatively complex as a result of the high temperature and high pressure,severe dogleg and buckling effects,which in some circumstances can even lead to string failure.Traditional computational methods for the analysis of these behaviors are often inaccurate.For this reason,here a more accurate mechanical model of the test string is introduced by considering variables such as temperature,pressure,wellbore trajectory,and buckling,as well as combining them with the deformation and string constraint conditions brought in by changes in temperature and pressure during the tripping,setting,and test operations.The model is validated by applying it to a specific high-pressure gas well(located in Northeast Sichuan).展开更多
To meet the requirements of marine natural gas hydrate exploitation,it is necessary to improve the penetration of completion sand control string in the large curvature borehole.In this study,large curvature test wells...To meet the requirements of marine natural gas hydrate exploitation,it is necessary to improve the penetration of completion sand control string in the large curvature borehole.In this study,large curvature test wells were selected to carry out the running test of sand control string with pre-packed screen.Meanwhile,the running simulation was performed by using the Landmark software.The results show that the sand control packer and screen can be run smoothly in the wellbore with a dogleg angle of more than 20°/30 m and keep the structure stable.Additionally,the comprehensive friction coefficient is 0.4,under which and the simulation shows that the sand control string for hydrate exploitation can be run smoothly.These findings have important guiding significance for running the completion sand control string in natural gas hydrate exploitation.展开更多
In the execution of method invocation sequences to test component security,abnormal or normal information is generated and recorded in a monitor log. By searching abnormal information from monitor log,the exceptions t...In the execution of method invocation sequences to test component security,abnormal or normal information is generated and recorded in a monitor log. By searching abnormal information from monitor log,the exceptions that the component has can be determined. To facilitate the searching process,string searching methods could be employed. However,current approaches are not effective enough to search long pattern string. In order to mine the specific information with less number of matches,we proposed an improved Sunday string searching algorithm in this paper. Unlike Sunday algorithm which does not make use of the already matched characters,the proposed approach presents two ideas — utilizing and recycling these characters. We take advantage of all matched characters in main string,if they are still in the matchable interval compared with pattern string,to increase the distance that pattern string moves backwards. Experimental analysis shows that,compared to Sunday algorithm,our method could greatly reduce the matching times,if the scale of character set constituting both main string and pattern string is small,or if the length of pattern string is long. Also,the proposed approach can improve the search effectiveness for abnormal information in component security testing.展开更多
AIM: Helicobacter pylori ( H pylofi) resistance after failed eradication has a major impact on the outcome of a further treatment regimen. The aim of this study was to assess the validity of a non-invasive strategy us...AIM: Helicobacter pylori ( H pylofi) resistance after failed eradication has a major impact on the outcome of a further treatment regimen. The aim of this study was to assess the validity of a non-invasive strategy using the 13C-urea breath test (UBT) and the gastric string test in identifying post-treatment resistance of Hpylori.METHODS: The UBT was routinely performed 4 to 6 wk after H pylorieradication therapy. Forty-two patients (24 females, 18 males, mean age 48 years) with a positive UBT were included in the study. A gastric string test using a capsule containing a 90 cm-long nylon fiber was performed.Before the capsule was swallowed, the free end of the string was taped to the cheek. After one hour in the stomach, the string was withdrawn. The distal 20 cm of the string was inoculated onto an agar plate and processed under microaerophilic conditions. Following the string test, upper gastrointestinal endoscopy was performed to obtain gastric biopsies for conventional culture.RESULTS: H pyloriwas successfully cultured from the gastric string in 34 patients (81%), but not in 5 patients due to contamination with oropharyngeal flora. Hpyloriwas cultured from the gastric biopsies obtained at endoscopy in 39 patients (93%).CONCLUSION: The UBT followed by the gastric string test in the case of treatment failure is a valid diagnostic strategy with the aim of determining the post-therapeutic antibiotic resistance of Hpyloriwith little inconvenience to the patient.Upper GI-endoscopy can be avoided in several cases by applying consequently this diagnostic package.展开更多
AIM:To evaluate the utility of the string test to detect genotypic clarithromycin-resistant Helicobacter pylori (H.pylori)by polymerase chain reaction(PCR)-restriction fragment length polymorphism.METHODS:Patients und...AIM:To evaluate the utility of the string test to detect genotypic clarithromycin-resistant Helicobacter pylori (H.pylori)by polymerase chain reaction(PCR)-restriction fragment length polymorphism.METHODS:Patients undergoing endoscopic examinations were enrolled in the present study.String tests were done on the next day of endoscopy.Segments of 23S rRNA were amplified from DNA obtained from string tests.PCR-restriction fragment length polymorphism was accomplished by restriction enzymes BbsI and BsaI recognizing the mutation site A to G at 2143or at 2142 of 23S rRNA domain V,respectively.RESULTS:One hundred and thirty-four patients with H.pylori infection underwent string tests.To compare phenotypic resistance,43 isolates were successfully cultured in 79 patients in whom 23S rRNA was successfully amplified.Of five patients with clarithromycinresistant H.pylori,23S rRNA of H.pylori isolates from four patients could be digested by BsaI.In 38 susceptible isolates,23S rRNA of H.pylori isolates from 36 patients could not be digested by either BsaI or BbsI.The sensitivity and specificity of the string test to detect genotypic clarithromycin resistance were 66.7%and97.3%,respectively.Positive and negative predictive values were 80%and 94.7%,respectively.CONCLUSION:String test with molecular analysis is a less invasive method to detect genotypic resistance before treatment.Further large-scale investigations are necessary to confirm our results.展开更多
In drilling field, stick-slip vibrations of the drill-string are the main reason for the failure of the drilling system. To suppress the undesired stick-slip vibrations, an observer-based state feedback control method...In drilling field, stick-slip vibrations of the drill-string are the main reason for the failure of the drilling system. To suppress the undesired stick-slip vibrations, an observer-based state feedback control method is proposed. The drilling system is described by a lumped parameter model including a Karnopp friction torque model. A state observer is designed to estimate the bit velocity in bottom hole and a state feedback controller is proposed to control the top drive velocity. By simulation, the performance of the control algorithm is demonstrated. Based on the control algorithm, a stick-slip vibration control system is developed. Test results show that the control system can effectively eliminate stick-slip vibrations of the drill-string and can be applied to the drilling field.展开更多
文摘The mechanical behavior of the test string in deep wells is generally relatively complex as a result of the high temperature and high pressure,severe dogleg and buckling effects,which in some circumstances can even lead to string failure.Traditional computational methods for the analysis of these behaviors are often inaccurate.For this reason,here a more accurate mechanical model of the test string is introduced by considering variables such as temperature,pressure,wellbore trajectory,and buckling,as well as combining them with the deformation and string constraint conditions brought in by changes in temperature and pressure during the tripping,setting,and test operations.The model is validated by applying it to a specific high-pressure gas well(located in Northeast Sichuan).
基金supported jointly by one of the major projects of Basic and Applied Basic Research in Guangdong Province“Key Basic Theory Research for Natural Gas Hydrate Trial Production in Shenhu Pilot Test Area”(2020B0301030003)the project from Southern Marine Science&Engineering Guangdong Laboratory Guangzhou City“Research on New Closed Circulation Drilling Technology without Riser”(GML2019ZD0501)the special project for hydrate from China Geological Survey“Trial Production Implementation for Natural Gas Hydrate in Shenhu Pilot Test Area”(DD20190226)。
文摘To meet the requirements of marine natural gas hydrate exploitation,it is necessary to improve the penetration of completion sand control string in the large curvature borehole.In this study,large curvature test wells were selected to carry out the running test of sand control string with pre-packed screen.Meanwhile,the running simulation was performed by using the Landmark software.The results show that the sand control packer and screen can be run smoothly in the wellbore with a dogleg angle of more than 20°/30 m and keep the structure stable.Additionally,the comprehensive friction coefficient is 0.4,under which and the simulation shows that the sand control string for hydrate exploitation can be run smoothly.These findings have important guiding significance for running the completion sand control string in natural gas hydrate exploitation.
基金supported by National Natural Science Foundation of China (NSFC grant number:61202110,61401180 and 61502205)the Postdoctoral Science Foundation of China (Grant number:2015M571687 and 2015M581739)the Graduate Research Innovation Project of Jiangsu Province(KYLX15_1079 and KYLX16_0900)
文摘In the execution of method invocation sequences to test component security,abnormal or normal information is generated and recorded in a monitor log. By searching abnormal information from monitor log,the exceptions that the component has can be determined. To facilitate the searching process,string searching methods could be employed. However,current approaches are not effective enough to search long pattern string. In order to mine the specific information with less number of matches,we proposed an improved Sunday string searching algorithm in this paper. Unlike Sunday algorithm which does not make use of the already matched characters,the proposed approach presents two ideas — utilizing and recycling these characters. We take advantage of all matched characters in main string,if they are still in the matchable interval compared with pattern string,to increase the distance that pattern string moves backwards. Experimental analysis shows that,compared to Sunday algorithm,our method could greatly reduce the matching times,if the scale of character set constituting both main string and pattern string is small,or if the length of pattern string is long. Also,the proposed approach can improve the search effectiveness for abnormal information in component security testing.
文摘AIM: Helicobacter pylori ( H pylofi) resistance after failed eradication has a major impact on the outcome of a further treatment regimen. The aim of this study was to assess the validity of a non-invasive strategy using the 13C-urea breath test (UBT) and the gastric string test in identifying post-treatment resistance of Hpylori.METHODS: The UBT was routinely performed 4 to 6 wk after H pylorieradication therapy. Forty-two patients (24 females, 18 males, mean age 48 years) with a positive UBT were included in the study. A gastric string test using a capsule containing a 90 cm-long nylon fiber was performed.Before the capsule was swallowed, the free end of the string was taped to the cheek. After one hour in the stomach, the string was withdrawn. The distal 20 cm of the string was inoculated onto an agar plate and processed under microaerophilic conditions. Following the string test, upper gastrointestinal endoscopy was performed to obtain gastric biopsies for conventional culture.RESULTS: H pyloriwas successfully cultured from the gastric string in 34 patients (81%), but not in 5 patients due to contamination with oropharyngeal flora. Hpyloriwas cultured from the gastric biopsies obtained at endoscopy in 39 patients (93%).CONCLUSION: The UBT followed by the gastric string test in the case of treatment failure is a valid diagnostic strategy with the aim of determining the post-therapeutic antibiotic resistance of Hpyloriwith little inconvenience to the patient.Upper GI-endoscopy can be avoided in several cases by applying consequently this diagnostic package.
基金Supported by Grants from National Science Council of Republic of China,No.NSC96-3111-P-042A-004-Y and No.NSC972314-B-037-047-MY3from Kaohsiung Medical University Hospital,No.KMUH97-7R32 and No.KMUH97-7G49
文摘AIM:To evaluate the utility of the string test to detect genotypic clarithromycin-resistant Helicobacter pylori (H.pylori)by polymerase chain reaction(PCR)-restriction fragment length polymorphism.METHODS:Patients undergoing endoscopic examinations were enrolled in the present study.String tests were done on the next day of endoscopy.Segments of 23S rRNA were amplified from DNA obtained from string tests.PCR-restriction fragment length polymorphism was accomplished by restriction enzymes BbsI and BsaI recognizing the mutation site A to G at 2143or at 2142 of 23S rRNA domain V,respectively.RESULTS:One hundred and thirty-four patients with H.pylori infection underwent string tests.To compare phenotypic resistance,43 isolates were successfully cultured in 79 patients in whom 23S rRNA was successfully amplified.Of five patients with clarithromycinresistant H.pylori,23S rRNA of H.pylori isolates from four patients could be digested by BsaI.In 38 susceptible isolates,23S rRNA of H.pylori isolates from 36 patients could not be digested by either BsaI or BbsI.The sensitivity and specificity of the string test to detect genotypic clarithromycin resistance were 66.7%and97.3%,respectively.Positive and negative predictive values were 80%and 94.7%,respectively.CONCLUSION:String test with molecular analysis is a less invasive method to detect genotypic resistance before treatment.Further large-scale investigations are necessary to confirm our results.
文摘In drilling field, stick-slip vibrations of the drill-string are the main reason for the failure of the drilling system. To suppress the undesired stick-slip vibrations, an observer-based state feedback control method is proposed. The drilling system is described by a lumped parameter model including a Karnopp friction torque model. A state observer is designed to estimate the bit velocity in bottom hole and a state feedback controller is proposed to control the top drive velocity. By simulation, the performance of the control algorithm is demonstrated. Based on the control algorithm, a stick-slip vibration control system is developed. Test results show that the control system can effectively eliminate stick-slip vibrations of the drill-string and can be applied to the drilling field.
