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
String validation routines have been widely used in many real-world applications,such as email validation and postcode validation.String test cases are adopted to test these validation routines,to identify potential d...String validation routines have been widely used in many real-world applications,such as email validation and postcode validation.String test cases are adopted to test these validation routines,to identify potential defects and security risks.Random Testing(RT)is a well-known testing approach to randomly generate string test cases from the input domain(i.e.,the set of all possible test inputs),which is simple to implement at a low cost.However,its testing effectiveness may be unsatisfactory for string validation routines.The main reason for this is that RT may have a high probability to generate invalid rather than valid string test cases,due to its randomness property.This research proposes a new RT approach based on the output types(i.e.,valid and invalid strings)for string validation routines,namely Output-type-guided Random Testing(RTO),which attempts to randomly generate both valid and invalid string test cases with a certain probability.This research performed an empirical study involving several real-world string validation routines collected from ten Java open-source projects,to investigate and compare testing performances of RT-O against the previous two widely-used RT methods.The results show that the generated string test cases by RT-O outperform test cases generated by other RT methods.展开更多
AIM: Helicobacter pylori (H pylori) 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 usi...AIM: Helicobacter pylori (H pylori) 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 H pylori. METHODS: The UBT was routinely performed 4 to 6 wk after H pylori eradication 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 micro-aerophilic conditions. Following the string test, upper gastrointestinal endoscopy was performed to obtain gastric biopsies for conventional culture. RESULTS: H pylori was successfully cultured from the gastric string in 34 patients (81%), but not in 5 patients due to contamination with oropharyngeal flora. H py/oriwas 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 H pylori with little inconvenience to the patient. Upper Gl-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.
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 by the Science and Technology Development Fund of Macao,Macao SAR(Nos.0021/2023/RIA1 and 0046/2021/A)a Faculty Research Grant of Macao University of Science and Technology(No.FRG-22-103-FIE)supported by the National Natural Science Foundation of China(Nos.61872167 and 61502205).
文摘String validation routines have been widely used in many real-world applications,such as email validation and postcode validation.String test cases are adopted to test these validation routines,to identify potential defects and security risks.Random Testing(RT)is a well-known testing approach to randomly generate string test cases from the input domain(i.e.,the set of all possible test inputs),which is simple to implement at a low cost.However,its testing effectiveness may be unsatisfactory for string validation routines.The main reason for this is that RT may have a high probability to generate invalid rather than valid string test cases,due to its randomness property.This research proposes a new RT approach based on the output types(i.e.,valid and invalid strings)for string validation routines,namely Output-type-guided Random Testing(RTO),which attempts to randomly generate both valid and invalid string test cases with a certain probability.This research performed an empirical study involving several real-world string validation routines collected from ten Java open-source projects,to investigate and compare testing performances of RT-O against the previous two widely-used RT methods.The results show that the generated string test cases by RT-O outperform test cases generated by other RT methods.
文摘AIM: Helicobacter pylori (H pylori) 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 H pylori. METHODS: The UBT was routinely performed 4 to 6 wk after H pylori eradication 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 micro-aerophilic conditions. Following the string test, upper gastrointestinal endoscopy was performed to obtain gastric biopsies for conventional culture. RESULTS: H pylori was successfully cultured from the gastric string in 34 patients (81%), but not in 5 patients due to contamination with oropharyngeal flora. H py/oriwas 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 H pylori with little inconvenience to the patient. Upper Gl-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.
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.
