For high reliability and long life systems, system pass/fail data are often rare. Integrating lower-level data, such as data drawn from the subsystem or component pass/fail testing,the Bayesian analysis can improve th...For high reliability and long life systems, system pass/fail data are often rare. Integrating lower-level data, such as data drawn from the subsystem or component pass/fail testing,the Bayesian analysis can improve the precision of the system reliability assessment. If the multi-level pass/fail data are overlapping,one challenging problem for the Bayesian analysis is to develop a likelihood function. Since the computation burden of the existing methods makes them infeasible for multi-component systems, this paper proposes an improved Bayesian approach for the system reliability assessment in light of overlapping data. This approach includes three steps： fristly searching for feasible paths based on the binary decision diagram, then screening feasible points based on space partition and constraint decomposition, and finally simplifying the likelihood function. An example of a satellite rolling control system demonstrates the feasibility and the efficiency of the proposed approach.展开更多
An experience is presented using the finite element method （FEM） and data mining （DM） techniques to develop models that can be used to optimieze the skin-pass rolling process based on its operating conditions. A F...An experience is presented using the finite element method （FEM） and data mining （DM） techniques to develop models that can be used to optimieze the skin-pass rolling process based on its operating conditions. A FE model based on a real skin-pass process is built and validated. Based on this model, a group of FE models is simulated with different adjustment parameters and with different materials for the sheet; both variables are chosen from pre-set ranges, From all FE model simulations, a database is generated; this database is made up of the above mentioned adjustment parameters, sheet properties and the variables of the process arising from the simulation of the model. Various types of data mining algorithms are used to develop predictive models for each of the variables of the process.The best predictive models can be used to predict experimentally hard-to-measure variables （internal stresses, internal straine, etc.） which are useful in the optimal design of the process or to be applied in real time control systems of a skin-pass process in -plant.展开更多
While adopting an elevation-over-azimuth architecture by an inter-satellite linkage antenna of a user satellite, a zenith pass problem always occurs when the antenna is tracing the tracking and data relay satellite （...While adopting an elevation-over-azimuth architecture by an inter-satellite linkage antenna of a user satellite, a zenith pass problem always occurs when the antenna is tracing the tracking and data relay satellite （TDRS）. This paper deals with this problem by way of, firstly, introducing movement laws of the inter-satellite linkage to predict the movement of the user satellite antenna followed by analyzing the potential pass moment and the actual one of the zenith pass in detail. A number of specific orbit altitudes for the user satellite that can remove the blindness zone are obtained. Finally, on the base of the predicted results from the movement laws of the inter-satellite linkage, the zenith pass tracing strategies for the user satellite antenna are designed under the program guidance using a trajectory preprocessor. Simulations have confirmed the reasonability and feasibility of the strategies in dealing with the zenith pass problem.展开更多
In order to continuously simulate multi-pass plate rolling process,a 3-D elastic hollow-roll model was proposed and an auto mesh-refining module with data passing was developed and integrated with FE software,Marc.The...In order to continuously simulate multi-pass plate rolling process,a 3-D elastic hollow-roll model was proposed and an auto mesh-refining module with data passing was developed and integrated with FE software,Marc.The hollow-roll model has equivalent stiffness of bending resistance and deformation to the real solid and much less meshes,so the computational time is greatly reduced.Based on these,the factors influencing plate profile,such as the roll-bending force,initial crown,thermal crown and heat transfer during rolling and inter-pass cooling can be taken into account in the simulation.The auto mesh-refining module with data passing can automatically refine and re-number elements and transfer the nodal and elemental results to the new meshes.Furthermore,the 3-D modeling routine is parametrically developed and can be run independently of Marc pre-processing program.A seven-pass industrial hot rolling process was continuously simulated to validate the accuracy of model.By comparison of the calculated results with the industrial measured data,the rolling force,temperature and plate profile are in good accordance with the measured ones.展开更多
基金supported by the National Natural Science Foundation of China(61304218)
文摘For high reliability and long life systems, system pass/fail data are often rare. Integrating lower-level data, such as data drawn from the subsystem or component pass/fail testing,the Bayesian analysis can improve the precision of the system reliability assessment. If the multi-level pass/fail data are overlapping,one challenging problem for the Bayesian analysis is to develop a likelihood function. Since the computation burden of the existing methods makes them infeasible for multi-component systems, this paper proposes an improved Bayesian approach for the system reliability assessment in light of overlapping data. This approach includes three steps： fristly searching for feasible paths based on the binary decision diagram, then screening feasible points based on space partition and constraint decomposition, and finally simplifying the likelihood function. An example of a satellite rolling control system demonstrates the feasibility and the efficiency of the proposed approach.
基金Item Sponsored by Spanish Ministry of Education and Science(DPI2007-61090)European Commission Research Programme of the Research Fund for Coal and Steel(RFS-PR-06035)
文摘An experience is presented using the finite element method （FEM） and data mining （DM） techniques to develop models that can be used to optimieze the skin-pass rolling process based on its operating conditions. A FE model based on a real skin-pass process is built and validated. Based on this model, a group of FE models is simulated with different adjustment parameters and with different materials for the sheet; both variables are chosen from pre-set ranges, From all FE model simulations, a database is generated; this database is made up of the above mentioned adjustment parameters, sheet properties and the variables of the process arising from the simulation of the model. Various types of data mining algorithms are used to develop predictive models for each of the variables of the process.The best predictive models can be used to predict experimentally hard-to-measure variables （internal stresses, internal straine, etc.） which are useful in the optimal design of the process or to be applied in real time control systems of a skin-pass process in -plant.
文摘While adopting an elevation-over-azimuth architecture by an inter-satellite linkage antenna of a user satellite, a zenith pass problem always occurs when the antenna is tracing the tracking and data relay satellite （TDRS）. This paper deals with this problem by way of, firstly, introducing movement laws of the inter-satellite linkage to predict the movement of the user satellite antenna followed by analyzing the potential pass moment and the actual one of the zenith pass in detail. A number of specific orbit altitudes for the user satellite that can remove the blindness zone are obtained. Finally, on the base of the predicted results from the movement laws of the inter-satellite linkage, the zenith pass tracing strategies for the user satellite antenna are designed under the program guidance using a trajectory preprocessor. Simulations have confirmed the reasonability and feasibility of the strategies in dealing with the zenith pass problem.
基金Project(20050248007) supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘In order to continuously simulate multi-pass plate rolling process,a 3-D elastic hollow-roll model was proposed and an auto mesh-refining module with data passing was developed and integrated with FE software,Marc.The hollow-roll model has equivalent stiffness of bending resistance and deformation to the real solid and much less meshes,so the computational time is greatly reduced.Based on these,the factors influencing plate profile,such as the roll-bending force,initial crown,thermal crown and heat transfer during rolling and inter-pass cooling can be taken into account in the simulation.The auto mesh-refining module with data passing can automatically refine and re-number elements and transfer the nodal and elemental results to the new meshes.Furthermore,the 3-D modeling routine is parametrically developed and can be run independently of Marc pre-processing program.A seven-pass industrial hot rolling process was continuously simulated to validate the accuracy of model.By comparison of the calculated results with the industrial measured data,the rolling force,temperature and plate profile are in good accordance with the measured ones.
