* De p t .o fMe c h .E n g. ,Ku mo hNa t i o n a lI n s t .Te c h (k h k i m@k u mo h. a c. k r) , * * De p t .o fI n t e l l i g e n tMe c h .E n g. ,Ku mo hNa t i o n a lI n s t .Te c h (c h h a n @k u mo h. a c. k r) , * * * De p t .o fMe c h .S y s t e m E n g. ,Ku mo hNa t i o n a lI n s t .Te c h (g i ma n @k u mo h. a c. k r)

No abstract

In this paper, the feasibility of the cost function having two control factors were discussed in compared to two others which has one different control factor respectively. As of the control factors, the dynamic response of a discrete system and the vibrational intensity at the reference point which is the connecting point of a discrete system to a flexible beam were controlled actively by the control force obtained from the minimization of the cost function. The method of feedforward control was employed for the control strategy. The reduction levels of the dynamic response of a discrete system and the vibrational intensity at a reference point, and also the input power induced by the control force were evaluated numerically in cases of the three different cost functions. In comparison with the results obtained from the cost functions of one control factor, which is the dynamic response or the vibrational intensity, in most cases of the cost function of two control factors the better or similar results were obtained. As a conclusion, it is surely noted that both the dynamic response and the vibrational intensity of the vibrating system be controlled up to the expected level by using the single cost function having two control factors.

In this study, the active control of active vibrational structural intensity (SI) in an infinite elastic plate is discussed. The plate is excited by mechanical noise sources, which generate a vector active SI field in the plate. A set of control actuators made up of point forces and point moments are located judiciously on the plate. The vibrational active SI-vector components are quadratic functions of the mechanical noise sources and control actuators magnitudes and phases. Thus the magnitude-squared active vector-SI at a sensor point is an expression with up to fourth power in the sources and actuators magnitudes and phases. An algorithm is developed to minimize the active SI using steepest descent on the gradient of the magnitude-squared total SI to obtain optimum values for magnitudes and phases of the control point actuators. Test cases are discussed to exhibit the influence of excitation structural wavelength, relative location of the control actuators to the mechanical noise source region, the orientation of the point moments, and the optimum combination of point forces and moments to minimize the total intensity in the near and far field. An attempt is made to explore actuators configurations that result in efficient local or global control. a)Currently Visiting Scholar at Penn State.

In a previous paper, the active control of active structural intensity (SI) in an infinite elastic plate was discussed. The plate is excited by mechanical noise sources, which generate a vector active SI field in the plate. A colocated point force and a point moment actuator at an arbitrary location on the plate were used. An algorithm was developed to minimize the active SI at a reference point on the plate. The control strategy was aimed at minimization of only the SI at a reference point. In this paper, the active control of SI in a desired zone or a large global area of the plate is explored through the use of multiple controllers spread over the plate. Furthermore, the cost function to be minimized also includes the required power injected by the controllers. Thus the minimization algorithm minimizes both the total SI in a zone as well as the total injected power by the controllers. The influence of the number and type of controllers, and the location of these controllers relative to the source region for the minimization of both the total SI in a region and the input mechanical power of these controllers, is explored. a)Currently Visiting Scholar at Penn State Univ.