Abdominal wall endometriosis may be caused by iatrogenic inoculation of the endometrium into the surgical wound. It is strongly recommended that, at the conclusion of the surgical procedure, the abdominal wound be cleaned thoroughly, particularly at both corner sites (especially the operators side). If an abdominal wall endometriosis is encountered after CS but the patient plans to have future pregnancy and the symptoms are mild, excision of the endometrioma may be deferred until the next indicated CS.

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This paper proposes robust loop-shaping techniques for a two-axis nano-positioning piezoelectric stage. Piezoelectric transducers are usually used to drive precision mechanisms because of their favorable properties, such as high resolution, high accuracy, and large driving force. However, the nonlinear characteristics of piezoelectric materials can degrade system performance. Therefore, we model a piezoelectric stage as a linear system, and regard its nonlinear factors as system uncertainties. Because robust control can guarantee stability and performance for systems with uncertainties and disturbances, we apply loop-shaping techniques and design standard robust controllers for the stage. In addition, we consider fixed-order robust control for the system in that controllers with lower orders are preferred for hardware implementation. Lastly, the designed controllers are implemented for experimental verification. The results demonstrate the effectiveness of these robust controllers in tracking reference signals and suppressing high-frequency vibrations.

The authors develop a step-and-align interference lithography system to fabricate large-area periodic submicron structures by stitching the unit exposure area step-by-step. A metal mask with a square transparent window in the center is used to intercept the quasi-flat-top region of the expanded Gaussian beam, and thus it serves as a beamshaper to approximate the ideal unit beam that has uniform intensity and spatial coherence. Two-dimensional precision dual-actuator motion stages could provide travel distance for full wafer exposure with 2 nm high precision positioning capability for stitching the submicron patterns. The gratings with period of 700 nm are successfully stitched along two directions on 100 mm diameter wafers.

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