In the originally proposed run-by-run control scheme, the EWMA statistic is used as an estimate of the process deviation from its target. However, the controller based on the EWMA statistic is not sufficient for controlling a wearing out process. The PCC controller has been thus proposed to enhance the run-by-run controller capability. In this paper, we first reexamine the fundamentals of the PCC formulations and propose an adjustment that is advantageous in controlling processes subject to both random shifts and drifts. The adjusted PCC controller is then further refined to take into account the process age. This age-based double EWMA scheme is then applied to the CMP process, which is known in the semiconductor industry to be rather unstable.
Simulation can be a very powerful tool to help decision making in many applications such as semiconductor manufacturing or healthcare, but exploring multiple courses of actions can be time consuming. We propose an optimal computing budget allocation (OCBA) method to improve the efficiency of simulation optimization using parametric regression. The approach proposed here, called OCBA-DOE, incorporates information from across the domain into a regression equation in order to efficiently allocate the simulation replications to improve the decision process. Asymptotic convergence rates of the OCBA-DOE method indicate that it offers a significant improvement when compared to a naïve allocation scheme and the traditional OCBA method. Numerical experiments reinforce these results.
Abstract:We search for CP violation in the decay D + → K 0 S K + using a data sample with an integrated luminosity of 977 fb −1 collected with the Belle detector at the KEKB e + e − asymmetric-energy collider. No CP violation has been observed and the CP asymmetry in D + → K 0 S K + decay is measured to be (−0.25 ± 0.28 ± 0.14)%, which is the most sensitive measurement to date. After subtracting CP violation due to K 0 −K 0 mixing, the CP asymmetry in D + →K 0 K + decay is found to be (+0.08 ± 0.28 ± 0.14)%.
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