Vibration mode analysis is by using commercial finite element software, and the analysis shows the sensitivity of the change ratio of the first order mode shape to the location and severity of structure damages.

2) The damage location method based on only changes in slopes of first order mode shape has been presented, that is to say, the change in slope of first order mode shape of the damaged storey must be greater than zero when only one storey is damaged. The above conclusion has been proved theoretically.

5) Three damage cases of the 10-storey shearing building are considered. Locations of damages can be identified using the method based on changes in slopes of first order mode shape.

Firstly,the locations of damage for shear frame structures were estimated by using the changes in the slope of the first order mode shape with measurement noise,which made the number of structural parameters to be identified decrease sharply.

Damages on a cantilever beam are simulated. Vibration mode analysis is by using commercial finite element software, and the analysis shows the sensitivity of the change ratio of the first order mode shape to the location and severity of structure damages. Hereby, the change ratio of the first order mode shape is presented as the indicator for structure damage detection.A successful identification of the location and severity of a structure damage is achieved by using artificial neural network.

A two-step detection of damage for shear frame structures was presented.Firstly,the locations of damage for shear frame structures were estimated by using the changes in the slope of the first order mode shape with measurement noise,which made the number of structural parameters to be identified decrease sharply.Through theoretical derivation,it was seen the change in the slope of the first order mode shape of damage element was greater than zero.Therefore,the location of damage can be estimated...

A two-step detection of damage for shear frame structures was presented.Firstly,the locations of damage for shear frame structures were estimated by using the changes in the slope of the first order mode shape with measurement noise,which made the number of structural parameters to be identified decrease sharply.Through theoretical derivation,it was seen the change in the slope of the first order mode shape of damage element was greater than zero.Therefore,the location of damage can be estimated by using it as a damage indicator.Then,according to artificial neural network(ANN) algorithm,the extent of structural damage is diagnosed using the first several order frequencies which can be measured accurately.It was demonstrated via numerical simulation that structural damage can be identified satisfactorily with great computational efficiency and high computational accuracy.

To reach the system stability by the revisable network of attitude control system for a launch vehicle under various conditions,the negative damp zero network with the characteristics of the same amplitude and phase lag was applied on the revisable network design to replace the conventional positive damp zero network in this paper.The realization of the negative damp zero network in the onboard computer,and the repeatability and stability were verified in the test.The application of the negative damp zero network...

To reach the system stability by the revisable network of attitude control system for a launch vehicle under various conditions,the negative damp zero network with the characteristics of the same amplitude and phase lag was applied on the revisable network design to replace the conventional positive damp zero network in this paper.The realization of the negative damp zero network in the onboard computer,and the repeatability and stability were verified in the test.The application of the negative damp zero network on the attitude control system of the first class for some launch vehicle showed that the system stability would be realized when the slope of first order mode shape near the mounting position of the rate gyro was positive.This method was valuable in the design of attitude control system for other launch vehicle.