As a prerequisite and a guarantee for safe and efficient natural gas hydrates(NGHs)exploitation,it is imperative to effectively determine the mechanical properties of NGHs reservoirs and clarify the law of the change ...As a prerequisite and a guarantee for safe and efficient natural gas hydrates(NGHs)exploitation,it is imperative to effectively determine the mechanical properties of NGHs reservoirs and clarify the law of the change in the mechanical properties with the dissociation of NGHs during NGHs production tests by depressurization.Based on the development of Japan’s two offshore NGHs production tests in vertical wells,this study innovatively proposed a new subsea communication technology-accurate directional connection using a wet-mate connector.This helps to overcome the technical barrier to the communication between the upper and lower completion of offshore wells.Using this new communication technology,this study explored and designed a mechanical monitoring scheme for lower completion(sand screens).This scheme can be used to monitor the tensile stress and radial compressive stress of sand screens caused by NGHs reservoirs in real time,thus promoting the technical development for the rapid assessment and real-time feedback of the in-situ mechanical response of NGHs reservoirs during offshore NGHs production tests by depressurization.展开更多
Search-based software engineering has mainly dealt with automated test data generation by metaheuristic search techniques. Similarly, we try to generate the test data (i.e., problem instances) which show the worst cas...Search-based software engineering has mainly dealt with automated test data generation by metaheuristic search techniques. Similarly, we try to generate the test data (i.e., problem instances) which show the worst case of algorithms by such a technique. In this paper, in terms of non-functional testing, we re-define the worst case of some algorithms, respectively. By using genetic algorithms (GAs), we illustrate the strategies corresponding to each type of instances. We here adopt three problems for examples;the sorting problem, the 0/1 knapsack problem (0/1KP), and the travelling salesperson problem (TSP). In some algorithms solving these problems, we could find the worst-case instances successfully;the successfulness of the result is based on a statistical approach and comparison to the results by using the random testing. Our tried examples introduce informative guidelines to the use of genetic algorithms in generating the worst-case instance, which is defined in the aspect of algorithm performance.展开更多
该文利用软件组件间信息流的传递过程,提出了基于风险分析的回归测试用例优先级排序算法(Risk Analysis-based Test Case Prioritization,RA-TCP).该算法针对现有的优先级排序技术未能有效利用测试用例所覆盖信息的问题,在类粒度下将软...该文利用软件组件间信息流的传递过程,提出了基于风险分析的回归测试用例优先级排序算法(Risk Analysis-based Test Case Prioritization,RA-TCP).该算法针对现有的优先级排序技术未能有效利用测试用例所覆盖信息的问题,在类粒度下将软件抽象为基于信息流的类级有向网络模型,然后将每个测试用例所覆盖的类间信息传递关系用一组杠铃模型表示,结合概率风险评估方法和故障树理论计算杠铃模型的风险值,最后以测试用例所覆盖的杠铃风险总和作为其排序依据.实验结果表明,风险越高的测试用例覆盖错误的可能性越大,RA-TCP算法提高了具有严重风险的错误发现速率,与7种排序算法对比,RA-TCP算法具有较高的错误检出率及较好的稳定性.展开更多
介绍了一种基于FSM(finite state machine)的生成一致性测试序列的改进算法,该方法混合了UIO(unique input/output)方法和T方法,UIO方法的测试能力优于T方法,但是生成的测试序列的长度较后者要长一些。实验结果表明,本改进方法的能力与...介绍了一种基于FSM(finite state machine)的生成一致性测试序列的改进算法,该方法混合了UIO(unique input/output)方法和T方法,UIO方法的测试能力优于T方法,但是生成的测试序列的长度较后者要长一些。实验结果表明,本改进方法的能力与UIO方法相同,并且测试序列的长度接近于T方法。展开更多
基金supported jointly by 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 in Guangzhou City“Research on New Closed Circulation Drilling Technology without Riser”(GML2019ZD0501).
文摘As a prerequisite and a guarantee for safe and efficient natural gas hydrates(NGHs)exploitation,it is imperative to effectively determine the mechanical properties of NGHs reservoirs and clarify the law of the change in the mechanical properties with the dissociation of NGHs during NGHs production tests by depressurization.Based on the development of Japan’s two offshore NGHs production tests in vertical wells,this study innovatively proposed a new subsea communication technology-accurate directional connection using a wet-mate connector.This helps to overcome the technical barrier to the communication between the upper and lower completion of offshore wells.Using this new communication technology,this study explored and designed a mechanical monitoring scheme for lower completion(sand screens).This scheme can be used to monitor the tensile stress and radial compressive stress of sand screens caused by NGHs reservoirs in real time,thus promoting the technical development for the rapid assessment and real-time feedback of the in-situ mechanical response of NGHs reservoirs during offshore NGHs production tests by depressurization.
文摘Search-based software engineering has mainly dealt with automated test data generation by metaheuristic search techniques. Similarly, we try to generate the test data (i.e., problem instances) which show the worst case of algorithms by such a technique. In this paper, in terms of non-functional testing, we re-define the worst case of some algorithms, respectively. By using genetic algorithms (GAs), we illustrate the strategies corresponding to each type of instances. We here adopt three problems for examples;the sorting problem, the 0/1 knapsack problem (0/1KP), and the travelling salesperson problem (TSP). In some algorithms solving these problems, we could find the worst-case instances successfully;the successfulness of the result is based on a statistical approach and comparison to the results by using the random testing. Our tried examples introduce informative guidelines to the use of genetic algorithms in generating the worst-case instance, which is defined in the aspect of algorithm performance.
文摘该文利用软件组件间信息流的传递过程,提出了基于风险分析的回归测试用例优先级排序算法(Risk Analysis-based Test Case Prioritization,RA-TCP).该算法针对现有的优先级排序技术未能有效利用测试用例所覆盖信息的问题,在类粒度下将软件抽象为基于信息流的类级有向网络模型,然后将每个测试用例所覆盖的类间信息传递关系用一组杠铃模型表示,结合概率风险评估方法和故障树理论计算杠铃模型的风险值,最后以测试用例所覆盖的杠铃风险总和作为其排序依据.实验结果表明,风险越高的测试用例覆盖错误的可能性越大,RA-TCP算法提高了具有严重风险的错误发现速率,与7种排序算法对比,RA-TCP算法具有较高的错误检出率及较好的稳定性.
文摘介绍了一种基于FSM(finite state machine)的生成一致性测试序列的改进算法,该方法混合了UIO(unique input/output)方法和T方法,UIO方法的测试能力优于T方法,但是生成的测试序列的长度较后者要长一些。实验结果表明,本改进方法的能力与UIO方法相同,并且测试序列的长度接近于T方法。
