SnO 2 films were prepared by plasma electrolytic oxidation technology in solution containing different SnO 2{ 3 concentrations. The structure and photocatalytic activity of the films were characterised by Xray diffraction, SEM, EDX, Brunauer-Emmett-Teller (BET) and UV-vis spectrophotometer. The result shows that films consisted of pure SnO 2 , but the grain size increased with the increase of SnO 2{ 3 concentration. Porous and rough SnO 2 films were formed on the substrate. The BET surface area increased with the increase of SnO 2{ 3 concentration and reached its maximum when the concentration of SnO 2{ 3 was 0?05M. The absorption edge of the films shifted from 370 to 408 nm when the concentration of SnO 2{ 3 increased from 0?01 to 0?03M. Degradation of rhodamine indicated that photocatalytic activity of film formed in 0?03M SnO 2{ 3 was highest due to its smaller grain, larger BET surface area and greater photon absorption.

Because the current actuator assemblies in hard disk drives (HDDs) are flexible systems, the resonant modes of the system inevitably limit its servo control bandwidth, which in turn limits the aerial density growth of HDDs, and also its shock robustness especially when HDDs are being increasingly deployed for consumer applications. The design and analysis method of a dynamic absorber to improve dynamic properties and shock resistance of HDDs is presented in this article. The HDD and the attached absorber were established and modeled as a 2 degrees-of-freedom (2DOF) system. The design parameters and structural configuration of the damping device, which is suitable for HDDs under base excitation, have been specified. Theoretical studies on the dynamic characteristics and shock resistance of the actuator assembly of the HDDs with attached dynamic absorbers have been described. The effectiveness of the dynamic absorber and the adopted design procedure are illustrated from the point of view of both bandwidth improvement and shock protection capacities. It has been clearly demonstrated that the introduction of a dynamic absorber into the actuator arm system, if properly designed, can greatly improve the capabilities of shock handling and residual vibration suppression in either operating or nonoperating conditions of HDDs.

The purpose of this paper is to develop both numerical and experimental methods that can be used for easy prediction of vibration characteristics of disk-spindle systems in hard disk drives (HDDs). First, the effective numerical method, i.e., Finite element method (FEM), for the modeling of the whole disks and spindle system under real product constraint conditions has been discussed. So the dynamics properties of the diskspindle system during the system design can be are analyzed conveniently. Finally, these analytical predictions by FEM are verified through the proposed modal testing setup. The dynamic characteristics of the whole assembly have been measured through externally induced excitations. Results obtained using 98 Yan et al.numerical and experimental methods agree very well. As demonstrated, the numerical methodology, i.e., FEM can provide much detailed information on the design of the disk-spindle system before it is built and tested to confirm the system design.

Many kinds of mechanical systems can be modeled as spatial rigid multibody systems (SR-MBS), which consist of a set of rigid bodies interconnected by joints, springs and dampers. Vibration calculation of SR-MBS is conventionally conducted by approximately linearizing the nonlinear equations of motion and constraint, which is very complicated and inconvenient for sensitivity analysis. A new algorithm based on constraint-topology transformation is presented to derive the oscillatory differential equations in three steps, that is, vibration equations for free SR-MBS are derived using Lagrangian method at first; then, an open-loop constraint matrix is derived to obtain the vibration equations for open-loop SR-MBS via quadric transformation; finally, a cut-joint constraint matrix is derived to obtain the vibration equations for closed-loop SR-MBS via quadric transformation. Through mentioned above, the vibration calculation can be significantly simplified and the sensitivity analysis can be conducted conveniently. The correctness of the proposed method has been verified by numerical experiments in comparison with the traditional approaches.