This paper describes the experimental application of adaptive control to Hybrid Squeeze Film Damper (HSFD) supported rotors. The HSFD has been shown to be an adaptive damper capable of providing infinite damper configurations between short and long damper configurations. Previously, theoretical investigations of the adaptive control of HSFD concentrated on the development of the model reference adaptive control (MRAC) method, as well as development of a nonlinear reference model. Simulations of the performance of the adaptive controller during run-up and coast-down indicated the superior performance of the adaptive controller. In this paper, the adaptive controller is tested on a multi-mode rotor. A test rig is designed and developed using computer control. A simple reference model is investigated consisting of a second order system. Three forms for adaptation gain are studied. The results of the experimental investigation illustrated the performance capabilities of the adaptive controller applied to the HSFD, and moreover indicated the possibility of simple design for the adaptive controller. [S0742-4795(00)01603-3]

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This paper describes the experimental application of adaptive control to Hybrid Squeeze Film Damper (HSFD) supported rotors. The HSFD has been shown to be an adaptive damper capable of providing infinite damper configurations between short and long damper configurations. Previously, theoretical investigations of the adaptive control of HSFD concentrated on the development of the model reference adaptive control (MRAC) method, as well as development of a nonlinear reference model. Simulations of the performance of the adaptive controller during run-up and coast-down indicated the superior performance of the adaptive controller. In this paper, the adaptive controller is tested on a multi-mode rotor. A test rig is designed and developed using computer control. A simple reference model is investigated consisting of a second order system. Three forms for adaptation gain are studied. The results of the experimental investigation illustrated the performance capabilities of the adaptive controller applied to the HSFD, and moreover indicated the possibility of simple design for the adaptive controller.

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Background: Glass fiber posts is the gold standard for the treatment of endodontically treated teeth with insufficient coronal tooth structure. Although it offers better retention and stress distribution when used, debonding is still the most common mode of failure for glass fiber posts.To overcome this problem, multiple surface treatments were tried to modify the post surface either chemically or mechanically to improve the post adhesion to resin cements. Objectives: To evaluate the pull-out bond strength of glass fiber posts to root dentin after different surface treatments using air-borne particle abrasion, diode laser and Er-Cr:YSGG laser. Materials and Methods: Forty freshly extracted single rooted teeth were root canal treated and divided into four groups according to surface treatment of the post: (Control, air borne-particle abrasion with alumina-oxide particles, irradiation with diode laser and irradiation with Er-Cr:YSGG). Pull-out test was done using a universal testing machine and the mode of failure of each sample was inspected under a stereomicroscope. Results: The Er-Cr:YSGG laser irradiation group showed the highest statistically significant bond strength value among all groups. Diode laser group showed the least bond strength value among all other groups significantly. No significant difference was found between air-borne particle abrasion and control groups. Conclusion: Er-Cr:YSGG laser irradiation improved the pull-out bond strength of the glass fiber post to root dentin compared to diode laser and air-borne particle abrasion.