Automatic scaling ionogram can get the parameters of ionogram which are vital to ionosphere detecting. In this paper, a new method is proposed to scale F2 layer trace automatically from oblique ionogram based on morph...Automatic scaling ionogram can get the parameters of ionogram which are vital to ionosphere detecting. In this paper, a new method is proposed to scale F2 layer trace automatically from oblique ionogram based on morphological operator and inversion technique. This method is verified through the comparison of actual detecting data with statistical analysis. The results show that the proposed automatic scaling method has high acceptable rate and is suitable for scaling oblique ionogram with different high angle wave states. It is fast and precise to fit O-mode echoes in F2 layer without the influence from F1 layer. This method could be applied in real-time ionospheric oblique sounding research with high reliability and versatility.展开更多
Modal parameters, including fundamental frequencies, damping ratios, and mode shapes, could be used to evaluate the health condition of structures. Automatic modal parameter identification, which plays an essential ro...Modal parameters, including fundamental frequencies, damping ratios, and mode shapes, could be used to evaluate the health condition of structures. Automatic modal parameter identification, which plays an essential role in realtime structural health monitoring, has become a popular topic in recent years. In this study, an automatic modal parameter identification procedure for high arch dams is proposed. The proposed procedure is implemented by combining the densitybased spatial clustering of applications with noise(DBSCAN) algorithm and the stochastic subspace identification(SSI). The 210-m-high Dagangshan Dam is investigated as an example to verify the feasibility of the procedure. The results show that the DBSCAN algorithm is robust enough to interpret the stabilization diagram from SSI and may avoid outline modes. This leads to the proposed procedure obtaining a better performance than the partitioned clustering and hierarchical clustering algorithms. In addition, the errors of the identified frequencies of the arch dam are within 4%, and the identified mode shapes are in agreement with those obtained from the finite element model, which implies that the proposed procedure is accurate enough to use in modal parameter identification. The procedure is feasible for online modal parameter identification and modal tracking of arch dams.展开更多
With an advanced foreign hydraulic automatic transmission as the objective,an analytical method for the gear-shifting schedule is proposed.First the demanded maximum gradient of test is estimated.Then a test scheme an...With an advanced foreign hydraulic automatic transmission as the objective,an analytical method for the gear-shifting schedule is proposed.First the demanded maximum gradient of test is estimated.Then a test scheme and analytical procedure is formulated by initial test and hypothetical shift parameters.Finally through gear-shifting tests under different road conditions,load,accelerator pedal position limitation,throttle opening and output shaft speed are found to be the gear-shifting parameters.Under a common road condition,the gear-shifting schedule is a double-parameter schedule.Based on the driver＇s demands on braking and dynamic performance,different shift schedules are made under downhill,uphill and quick releasing acceleration pedal conditions.The operation criteria of down-shift schedule on abrupt grade are proposed.展开更多
Aimed at the problem that the traditional suppressed fuzzy C-means clustering algorithms ignore the real needs of different objects, applying the same suppressed parameter for modifying membership degrees of all the o...Aimed at the problem that the traditional suppressed fuzzy C-means clustering algorithms ignore the real needs of different objects, applying the same suppressed parameter for modifying membership degrees of all the objects, a novel partition region-based suppressed fuzzy C-means clustering algorithm with better capacity of adaptability and robustness is proposed in this paper. The model based on the real needs of different objects is built, making it clear to decide whether to proceed with further determination; in addition, the external user-defined suppressed parameter is automatically selected according to the intrinsic structural characteristic of each dataset, making the proposed method become robust to the fluctuations in the incoming dataset and initial conditions. Experimental results show that the proposed method is more robust than its counterparts and overcomes the weakness of the original suppressed clustering algorithm in most cases.展开更多
At present,shale gas exploration and development in China is faced with some problems,such as the imperfect evaluation system of reservoir effectiveness and the limitations of reservoir evaluation system on efficient d...At present,shale gas exploration and development in China is faced with some problems,such as the imperfect evaluation system of reservoir effectiveness and the limitations of reservoir evaluation system on efficient development of shale gas.In order to improve the content and the standard of reservoir evaluation,this paper analyzed the shortcomings and challenges in the static evaluation of shale gas reservoirs on the basis of existing reservoir evaluation,and established a method for evaluating shale gas reservoir effectiveness and a scheme for classifying pore systems.Then,the dynamic evaluation parameters after shale fracturing and their effects on drainage and production measures were discussed.In addition,the potential evaluation parameters of“automatic mitigating water blocking”were studied,and a comprehensive reservoir evaluation system of“staticedynamic”combination was established.And the following research results were obtained.First,new challenges to the shale gas reservoir evaluation are emerged as the lack of in-depth study on“reservoir effectiveness,dynamic evaluation parameter system after fracturing and drainage and production measures after fracturing”,which leads to the serious lag of existing shale gas reservoir evaluation system behind production.Second,the evaluation of reservoir effectiveness is mainly presented as the evaluation on the lower limit of effective porosity,and is embodied in the influence of clay bound water and unconnected pores on the development of shale gas.Third,the development of shale gas reservoir evaluation follows the trend of refining the static reservoir evaluation parameters,defining the potential evaluation indexes of“automatic mitigating water blocking”and establishing the reservoir comprehensive evaluation system of“staticedynamic”combination.Fourth,a post-frac dynamic evaluation system is determined for the potential evaluation indexes of“automatic mitigating water blocking”(e.g.,wettability,water imbibition retention capacity,water imbibition expansion mode,expansion rate,and water imbibition cracking capacity).Fifth,a reservoir evaluation idea is put forward that“static evaluation of shale gas reservoir is the foundation and postfrac dynamic evaluation is the complement”,and a comprehensive reservoir evaluation system is established of“staticedy-namic”combination suitable for the evaluation of marine shale gas reservoirs in China.展开更多
We launch P_(ARF)—a toolkit for adaptively tuning abstraction strategies of static program analyzers in a fully automated manner.P_(ARF) models various types of external parameters(encoding abstraction strategies)as ...We launch P_(ARF)—a toolkit for adaptively tuning abstraction strategies of static program analyzers in a fully automated manner.P_(ARF) models various types of external parameters(encoding abstraction strategies)as random variables subject to probability distributions over latticed parameter spaces.It incrementally refines the probability distributions based on accumulated intermediate results generated by repeatedly sampling and analyzing,thereby ultimately yielding a set of highly accurate abstraction strategies.P_(ARF) is implemented on top of F_(RAMA)-C/E_(VA)—an off-the-shelf open-source static analyzer for C programs.P_(ARF) provides a web-based user interface facilitating the intuitive configuration of static analyzers and visualization of dynamic distribution refinement of the abstraction strategies.It further supports the identification of dominant parameters in F_(RAMA)-C/E_(VA) analysis.Benchmark experiments and a case study demonstrate the competitive performance of P_(ARF) for analyzing complex,large-scale real-world programs.展开更多
基金Supported by the National Natural Science Foundation of China(59975035,41006058)the Fundamental Research Funds for the Central Universities(2014212020205)
文摘Automatic scaling ionogram can get the parameters of ionogram which are vital to ionosphere detecting. In this paper, a new method is proposed to scale F2 layer trace automatically from oblique ionogram based on morphological operator and inversion technique. This method is verified through the comparison of actual detecting data with statistical analysis. The results show that the proposed automatic scaling method has high acceptable rate and is suitable for scaling oblique ionogram with different high angle wave states. It is fast and precise to fit O-mode echoes in F2 layer without the influence from F1 layer. This method could be applied in real-time ionospheric oblique sounding research with high reliability and versatility.
基金National Natural Science Foundation of China under Grant Nos. 51725901 and 51639006。
文摘Modal parameters, including fundamental frequencies, damping ratios, and mode shapes, could be used to evaluate the health condition of structures. Automatic modal parameter identification, which plays an essential role in realtime structural health monitoring, has become a popular topic in recent years. In this study, an automatic modal parameter identification procedure for high arch dams is proposed. The proposed procedure is implemented by combining the densitybased spatial clustering of applications with noise(DBSCAN) algorithm and the stochastic subspace identification(SSI). The 210-m-high Dagangshan Dam is investigated as an example to verify the feasibility of the procedure. The results show that the DBSCAN algorithm is robust enough to interpret the stabilization diagram from SSI and may avoid outline modes. This leads to the proposed procedure obtaining a better performance than the partitioned clustering and hierarchical clustering algorithms. In addition, the errors of the identified frequencies of the arch dam are within 4%, and the identified mode shapes are in agreement with those obtained from the finite element model, which implies that the proposed procedure is accurate enough to use in modal parameter identification. The procedure is feasible for online modal parameter identification and modal tracking of arch dams.
基金Supported by the National High Technology Research and Development Program of China(863 Program)(2012AA112101)
文摘With an advanced foreign hydraulic automatic transmission as the objective,an analytical method for the gear-shifting schedule is proposed.First the demanded maximum gradient of test is estimated.Then a test scheme and analytical procedure is formulated by initial test and hypothetical shift parameters.Finally through gear-shifting tests under different road conditions,load,accelerator pedal position limitation,throttle opening and output shaft speed are found to be the gear-shifting parameters.Under a common road condition,the gear-shifting schedule is a double-parameter schedule.Based on the driver＇s demands on braking and dynamic performance,different shift schedules are made under downhill,uphill and quick releasing acceleration pedal conditions.The operation criteria of down-shift schedule on abrupt grade are proposed.
基金supported by the National Natural Science Foundation of China(61401363)the Science and Technology on Avionics Integration Laboratory and Aeronautical Science Foundation(20155153034)+1 种基金the Fundamental Research Funds for the Central Universities(3102016AXXX0053102015BJJGZ009)
文摘Aimed at the problem that the traditional suppressed fuzzy C-means clustering algorithms ignore the real needs of different objects, applying the same suppressed parameter for modifying membership degrees of all the objects, a novel partition region-based suppressed fuzzy C-means clustering algorithm with better capacity of adaptability and robustness is proposed in this paper. The model based on the real needs of different objects is built, making it clear to decide whether to proceed with further determination; in addition, the external user-defined suppressed parameter is automatically selected according to the intrinsic structural characteristic of each dataset, making the proposed method become robust to the fluctuations in the incoming dataset and initial conditions. Experimental results show that the proposed method is more robust than its counterparts and overcomes the weakness of the original suppressed clustering algorithm in most cases.
基金supported by the National Natural Science Foundation of China"Characterization of the Nanopore Structure and Research on Seepage in Shale Reservoir"(No.:51674044)the Applied Basic Research Project of the Sichuan Province"Research on Intelligent Evaluation System for Key Production Zone of Marine Shale Gas(Provincial Significant Project)"(No.:2019YJ0346)+1 种基金the Significant Emerging Enginecring Project of the Sichuan Province"Research on the method of evaluating the effectiveness of fracturing the shak gas reservoir on the basis of fracturing fluid flow-back law"(No.:2019JDRC0095)the Overseas Expertise Introduction Project for Discipline Innovation(111 project)"Base of Overseas Expertise Introduction for Discipline Innovation of High-Efficiency Development of Deep-Layer Marine Shale Gas"(No.:D18016).
文摘At present,shale gas exploration and development in China is faced with some problems,such as the imperfect evaluation system of reservoir effectiveness and the limitations of reservoir evaluation system on efficient development of shale gas.In order to improve the content and the standard of reservoir evaluation,this paper analyzed the shortcomings and challenges in the static evaluation of shale gas reservoirs on the basis of existing reservoir evaluation,and established a method for evaluating shale gas reservoir effectiveness and a scheme for classifying pore systems.Then,the dynamic evaluation parameters after shale fracturing and their effects on drainage and production measures were discussed.In addition,the potential evaluation parameters of“automatic mitigating water blocking”were studied,and a comprehensive reservoir evaluation system of“staticedynamic”combination was established.And the following research results were obtained.First,new challenges to the shale gas reservoir evaluation are emerged as the lack of in-depth study on“reservoir effectiveness,dynamic evaluation parameter system after fracturing and drainage and production measures after fracturing”,which leads to the serious lag of existing shale gas reservoir evaluation system behind production.Second,the evaluation of reservoir effectiveness is mainly presented as the evaluation on the lower limit of effective porosity,and is embodied in the influence of clay bound water and unconnected pores on the development of shale gas.Third,the development of shale gas reservoir evaluation follows the trend of refining the static reservoir evaluation parameters,defining the potential evaluation indexes of“automatic mitigating water blocking”and establishing the reservoir comprehensive evaluation system of“staticedynamic”combination.Fourth,a post-frac dynamic evaluation system is determined for the potential evaluation indexes of“automatic mitigating water blocking”(e.g.,wettability,water imbibition retention capacity,water imbibition expansion mode,expansion rate,and water imbibition cracking capacity).Fifth,a reservoir evaluation idea is put forward that“static evaluation of shale gas reservoir is the foundation and postfrac dynamic evaluation is the complement”,and a comprehensive reservoir evaluation system is established of“staticedy-namic”combination suitable for the evaluation of marine shale gas reservoirs in China.
基金supported by the Zhejiang Provincial Natural Science Foundation Major Program under Grant No.LD24F020013the CCF-Huawei Populus Grove Fund under Grant No.CCF-HuaweiFM202301+1 种基金the Fundamental Research Funds for the Central Universities of China under Grant No.226-2024-00140the Zhejiang University Education Foundation's Qizhen Talent Program.
文摘We launch P_(ARF)—a toolkit for adaptively tuning abstraction strategies of static program analyzers in a fully automated manner.P_(ARF) models various types of external parameters(encoding abstraction strategies)as random variables subject to probability distributions over latticed parameter spaces.It incrementally refines the probability distributions based on accumulated intermediate results generated by repeatedly sampling and analyzing,thereby ultimately yielding a set of highly accurate abstraction strategies.P_(ARF) is implemented on top of F_(RAMA)-C/E_(VA)—an off-the-shelf open-source static analyzer for C programs.P_(ARF) provides a web-based user interface facilitating the intuitive configuration of static analyzers and visualization of dynamic distribution refinement of the abstraction strategies.It further supports the identification of dominant parameters in F_(RAMA)-C/E_(VA) analysis.Benchmark experiments and a case study demonstrate the competitive performance of P_(ARF) for analyzing complex,large-scale real-world programs.
