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Correlation diagnosis in multivariate process quality management is an important and challenging issue. In this paper, a new approach based on the optimal typical correlated component pair group (OTCCPG) is proposed. Firstly, the theorem of correlation decomposition is proved to decompose the correlation of all the quality components as serial correlations of component pairs, and then according to the transitivity of correlations of component pairs, the decomposition result is represented by a correlation set of typical correlated component pairs. Finally, an algorithm for OTCCPG based on the maximum correlation spanning tree (MCST) is proposed, and T2 control charts to monitor the correlations of component pairs in OTCCPG are established to form the correlation diagnostic system. Theoretical analysis and practice prove that the proposed method could reduce the space complexity of the diagnostic system greatly. [ABSTRACT FROM AUTHOR]

Radio frequency blackout indicates the communication interruption between signal monitoring sites and re-entry vehicles; it is a serious threat to the safety of astronauts and the space exploration missions. In this study, a surface catalytic model coupled with a thermochemical non-equilibrium computational fluid dynamic model is developed to study the catalytic wall effect on the plasma sheath of a hypersonic re-entry vehicle. The mechanism of the surface catalytic effect on the plasma sheath of a re-entry capsule is revealed by a comparative study. The flow-field characteristics simulated under conditions of the full-catalytic and non-catalytic walls are compared and discussed for the hypersonic atmospheric re-entry capsule at different altitudes. The chemical and physical mechanisms behind the surface catalytic effect of the re-entry capsule are analyzed. The experimental data of Radio Attenuation Measurement-C-II are used to validate the numerical model established in the present study. It is found that the numerical results simulated with the fully catalytic wall are more consistent with the experimental data. Near the capsule wall, the mole fractions of the species N, O, N+, and O+ decrease as the catalytic recombination coefficient increases. Because of the surface catalytic effect, the communication black is mitigated due to the reduction of the electron number density in the wake zone of the capsule. [ABSTRACT FROM AUTHOR]

In this study, a method for simulating the whole transient process of the cavitation evolution in a diesel injector was proposed. Diesel is taken as the fuel. The basic characteristics of partial, local, and super cavitation phenomena inside the injector were reproduced and discussed at different time steps. On the basis of movement features of the injector needle, Firstly, the moving process of the diesel injection such as the upward, suspension, and downward movements were simulated under different injector geometric parameters. The time-dependent movement process of the injector needle were controlled by a user-defined program developed by ourselves. Thereafter, a dynamic grid system and a two-phase flow cavitation numerical model were constructed and adopted to numerically reproduce the two-phase flow and the cavitation inside the injector. It was found that the volume fraction of the gas diesel during the partial cavitation is greater than that during the super-cavitation. The faster the needle valve opens, the earlier super-cavitation forms, but the gas volume fraction of diesel decreases faster in the injection orifice. Increasing the drain orifice diameter is helpful for earlier formation of the super-cavitation. [ABSTRACT FROM AUTHOR]