Ba 0.85 Ca 0.15 Ti 0.9 Zr 0.1 O 3 powders were synthesized by sol-gel processing and Ba 0.85 Ca 0.15 Ti 0.9 Zr 0.1 O 3 ÀxCuO piezoelectric ceramics were prepared using the as-prepared powders. Microstructures and electric properties of the ceramics were studied, especially, the effects of CuO additive on the sintering characteristics and electric properties. Both the performance and the sintering behaviour of BCTZ ceramics are improved by using as-prepared Ba 0.85 Ca 0.15 Ti 0.9 Zr 0.1 O 3 powders and CuO as a sintering aid. BCTZ ceramic with 1.5 mol% CuO exhibits good electric properties: e r $ 5338 (10 kHz), tan d $ 0.014 (10 kHz), d 33 $ 670 pC N À1 and k p $ 57.8% at room temperature. Figure 8 (online colour at: www.pss-a.com) Sintering temperature dependence of k p (a) and Q m (b) values for BCTZ-xCuO ceramics.

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Highly robust mesh deformation methods are key techniques for solving unsteady flow field problems with moving or deforming boundaries. Because it is imperative to reduce the remeshing times, these methods are important in engineering applications, especially for complex geometric boundaries and large displacements. We introduce three classical elasticity-based mesh deformation methods and determine the limitations of the two nonlinear classical methods. Two steps were taken to achieve an integrated improvement: first, the robust power parameters a and b and the weighted parameter x are introduced to enhance the robustness of the basic elasticity equation. Second, a mesh quality parameter is implemented to prevent the large distortion of the poor elements and this parameter is added to the elasticity equation as a constraint. To validate the validity of the integrated improvement approach, several test cases of a moving or deforming two-dimensional flat plate are used. Additionally, two simulated engineering examples are used to demonstrate the application of the integrated improvement for practical problems, including the pitching oscillation of a National Advisory Committee for Aeronautics (NACA) 0012 airfoil and the ONERA M6 wing. The results show that the integrated improvement approach does not only allow for the selection of suitable robust parameters to achieve more robust deformed meshes but also reduces the distortion of the poor elements near the moving boundary, even when the deformation is severe.

Integral solid propellant ramjet (ISPR) supersonic cruise vehicles share the characteristic that they are highly integrated configurations. The traditional design of vehicles cannot achieve a balance between computational expense and accuracy. A multifidelity multidisciplinary design optimization (MDO) platform has been developed in this study. The focus of the platform is on ISPR supersonic cruise vehicles. Firstly, codes of discipline with different levels of fidelity (LoF) were established, such as geometry, aerodynamics, radar cross-section calculations, propulsion, mass, and trajectory discipline codes. Secondly, two MDO frameworks were constructed through discipline codes. A low LoF MDO framework is suitable for conceptual design, and a medium LoF MDO framework is suitable for preliminary design. Finally, taking the optimization problem with the minimum overall detection probability of flight trajectory as an example, the low LoF framework first explores the entire design space to achieve the mission requirements, and then, the medium LoF MDO framework accepts the low LoF framework optimization parameters. Hence, the optimization target is reached with more detailed parameters and higher fidelity. Additionally, an example for a solid propellant missile with minimum total mass is tested by the platform. The study results show that the multifidelity MDO framework not only exploits interactions between the disciplines but also improves the accuracy of optimization results and reduces the iteration time.

Pure tetragonal phase Ba 0.96 Sr 0.04 Zr 0.04 Y 0.005 Ti 0.955 O 2.9975 nano-powders were synthesized via a simple, fast and low cost method: polyacrylamide gel (PAG) method.The effects of processing parameters on the polymerization reaction and the sizes of as-prepared powder were investigated. The results reveal that the critical value of monomer / cross-linking agent ratio is 4.5:1 for the tightest network structure and the smallest average particle size of nano-powder correspondingly due to the smallest grid of gel. The monomer/cross-linking agent ratio and the concentration of cross-linking agent have significant influence on the gel quality and particle. In the investigation range we have probed into, the nano-dispersed BSZYT powders is obtained. The average native grain size of as-prepared powder is ∼27 and ∼45 nm after calcined at 900 • C and 1200 • C, respectively.