Based on transfer matrix method for multibody system, the dynamics model of a certain multiple launch rockets system (MLRS), the topology figure of dynamics model, the numerical dynamics simulation system are established, and the dynamic characteristics of MLRS in different working conditions are compared. Then continuous variables for joint optimization are designed for firing orders and firing intervals, combining with the Genetic Algorithms, the optimal design of firing orders and firing intervals for the purpose of the best firing dispersion in different working conditions is focused in a real case. The results of simulation show that the firing dispersion has been improved more than 30%. Based on chip microprocessor technology, a self-adaption firing device is manufactured, which receives good achievement in engineering application. Thus, the launch technique of variant firing orders and variant firing intervals for MLRS has been realized.
 

Modal analysis and parameter identification are key technologies for structural dynamics. While the range of its applications is continuously expanding, the higher analysis challenges are increasing as well. A best model order is defined on the consideration of the existence of the noise modals in orthogonal polynomial algorithm, which is most widely used in modal analysis. Unfortunately, the minimum error could not be well satisfied simultaneously. Demand for dividing the frequency range into several sub-bands is due to numerical instabilities and calculation problem with the increase of the model order. The VF algorithm decomposed the rational function by using a common set of partial fractions as basis functions. The acquisition order of the modal is based on the modal energy, which ensures the fast convergence of VF algorithm. Stabilities both on parameters of the partial fractions and numerical are acquired with the increase of the model order. In this paper, a brief review of VF is presented and the feasibility of VF in modal analysis is demonstrated. The refinement of the FRFs curve fitting is achieved by a detailed description on deviation analysis stability of the parameters and order selection. An aerospace case study is discussed and compared with another algorithm.
 

Over the last few decades, there has been great interest in the development of a structural health moni-toring (SHM) methodology based on vibration data. The quantity and quality of the measured data, i.e., the number of sensors and the corresponding locations are very important for the success of SHM utilizing measured dynamic re-sponses. In order to extract the most information from the measured data and reduce the uncertainties of the identified model parameters, a methodology of optimal sensor configuration for structural model parameters identification is pre-sented. In order to avoid the influence of modeling error induced by traditional finite element method based on static shape function on the results of structural dynamic characteristics and optimal sensor placement, spectral finite element method being a dynamic modeling method with high-accuracy is employed to model the target structure in the proposed methodology. In addition, minimum of the uncertainties in model parameter estimates is taken as the optimality criterion for placing sensors, and information entropy measure is used to quantify these uncertainties which are calculated by the Bayesian statistical identification methodology. The information entropy measure is minimized over the set of possible sensor configurations to optimally locate a given number of sensors by an integer-coded genetic algorithm. Both nu-merical simulation and laboratory experiment are carried out for a periodic pipe-beam model with flexible joints on elastic foundations to verify the proposed methodology.

The stochastic resonance in Bistable Duffing System is studied in this paper. For the large parameter condition which does not meet the adiabatic approximation, a kind of adaptive stochastic resonance weak signal detection system based on frequency control is proposed in this paper. It can detect the unknown high frequency weak signal. The simulation results show that the system can realize high frequency signal stochastic resonance. Compared with the traditional stochastic resonance system, its precision and system output signal-to-noise ratio is greatly improved, and its application in the weak signal detection field is extended.
 

To prevent the leakage accidents of pipes and boiler, the key lies in whether the signals of cracks and small leaks can be detected effectively. For the problem of acoustic emission signals detection, a new method of detecting acoustic emission signals based on RQA and SVM was described. Firstly, the theory of wavelet threshold de-noising was used to reduce the noise signal. Secondly, the principle of RQA was borrowing to detection of acoustic emission signal, by calculation, we can get some quantifiable feature parameters. Using these parameters as SVM input parameters, the simulation acoustic emission signals of cracks can be identified. In the experimental conditions, the feasibility of this method has been validated.
 

On the basis of considering radial clearance and the changing of contact deformation when defect rolling element passing inner and outer ring, an intershaft bearing dynamic model with local defect rolling element was established under two kinds of supporting form. The vibration effect of different supporting form and different rotating direction of inner and outer ring were comparatively researched in this paper. The result shows that，the vibration amplitude of the supporting structure with the inner ring bearing in the high-pressure rotor and the outer ring bearing in the low-pressure rotor is bigger than the supporting structure with the inner ring bearing in the low-pressure rotor and the outer ring bearing in the high-pressure rotor；compared to inner and outer ring counter-rotating, the vibration amplitude of inner and outer ring co-rotating was bigger；although the impact amplitude was small and it was not conducive to find fault when inner and outer ring counter-rotating, it is more frequently that the defect attacks the rolling element, so under the same operating condition, the co-rotating intershaft bearing has a larger potential risk；the rotating frequency of cage was the main modulation frequency of intershaft bearing vibration signal, and compared to inner and outer ring co-rotating, the modulation effect of inner and outer ring counter-rotating was more intense.
 

A multi-ojective optimization technique is presented to solve the problem of EOD manipulators’ trajectory planning.At first, cubic splines are used to connect every pair of consecutive via-points. Two virtual points are introduced to ensure the initial and final conditions for velocity and acceleration can be respected. Manipulability objective is developed to enhance the manipulability of mechanism. The objective functions and kinematic constraints are presented by parameters of cubic spine, so that the problem transform into the optimization of every time interval. Second, constraint NSGA-II is adopted to plan the multi-objective trajectory， which is suitable to solving optimization problems with nonlinear constraints. The process of algorithm based on NSGA-II is created. Finally, compared to traditional method, simulation results proposed that the developed technique improve the manipulability effectively and every optimizing index is better than the results of linear weighting coefficient technique. The obtained trajectories are smooth enough and easy to control.
 

In order to optimize the influencing parameters of seismic performance about rectangular concrete filled steel tube (CFST) column, a bottom strengthened rectangular CFST column whose bottom zone was welded with enhancing steel plates, was proposed. Based on the experimental results, the factors affecting the load-bearing capacity were analyzed. By means of the finite element analysis software ABAQUS, the analysis to simulate numerically the specimens with different compression ratio, different strength grade of concrete, different height and thickness of the bottom strengthened steel plate were carried out. The analytical results were compared with the experimental results. The study shows: when the axial compression ratio increases, the load-bearing capacity and the ductility decrease; when the strength grade of concrete increases, the bearing capacity also increases, but the decline steepens and the ductility decreases; when the height of the strengthened plate increases, the load-bearing capacity of specimens increases steadily, the energy dissipation capacity increases, and the ductility is approximately equal to each other; when the thickness of the strengthened plate increases, the load-bearing capacity improves only a little. The rectangular concrete filled steel tube column with bottom enhancing plates shows better seismic behavior and higher energy dissipation capacity if suitable constructional requirements are satisfied. Such structural configuration can be adopted in design of high-rise buildings.
 

In order to further reveal the propagation attenuation laws of blasting vibration based on damage accumulation, author designed damage accumulation and blasting vibration testing experiment of concrete block. The results show that the damage value of the measured points went on increasing with the increase of the blasting times. The damage value can be divided into two stages in middle and far area, a slow increase at early stage and a quick increase at later stage. Single blasting vibration velocity of measured points decreased with the distance increasing, and vibration velocity of measured points in the near area decreased faster than the middle and far area. The blasting vibration velocity of measured points went on decreasing generally with the increase of the blasting times, and the vibration velocity near the explosion source decreased rapidly, But In middle and far area, the velocity decreased in small amplitude and slowly. And with the increase of the blasting times, the vibration velocity has the process of sudden increase. The vibration attenuation coefficient increased slowly with the increase of blasting times, however, the value of  reduced, and both of them had a process of small amplitude distortion. Under the condition of repeated blasting, the determination of the safety threshold and propagation attenuation laws（the value of  and ）of the blasting vibration should take full account of the blasting vibration damage accumulation effect. 
 

 

In order to explore mechanism of extension of the nearby crack defects in the roadway under explosion load, transmission type dynamic caustics experimental system is adopted to carry out the simulated experimental study. The experimental results show that the propagation mechanism of recessive crack which is located at meeting-blast side results from that the existing tunnel makes the leading effect of prefabricated crack more notable, which guides the propagation crack from the explosive source meets the left cutting-edge of prefabricated crack and diffract to the right cutting-edge, the right cutting-edge start to extend under the stretching influence of diffraction wave, when the distance between the prefabricated crack and the left panel of tunnel is 10 mm. For prefabricated recessive crack of back-blast side, when the spacing between the prefabricated crack and the right panel of tunnel is 4 mm, the expansion of crack result from that weak free surface of roadway guides the diffraction stress wave to crack defects, crack extends subjected to tensile stress. Compare the prefabricated crack extension condition when roadway exists with that of no roadway, the existing roadway increases dynamic stress concentration at the crack defects, inducing crack extension under the effect of the explosive stress wave.