The placement optimization of piezoelectric actuators and active vibration control of a membrane structure are studied in this paper. The classical linear quadratic regulator con- trollers are designed to suppress the...The placement optimization of piezoelectric actuators and active vibration control of a membrane structure are studied in this paper. The classical linear quadratic regulator con- trollers are designed to suppress the unwanted vibration. Simulation results indicate that the optimal locations of piezoelectric actuators are affected deeply by the additional mass and stiff- ness of actuators, the computational efficiency of particle swarm optimizer is higher than that of genetic algorithm for this particular problem, and the control performance of optimally placed actuators is better than that of non-optimally placed actuators.展开更多
Additive Manufacturing(AM) processing has attracted wide attention due to its advantages, e.g., rapid prototyping and free design. In aeronautic and astronautic engineering, it is especially attractive to apply AM pro...Additive Manufacturing(AM) processing has attracted wide attention due to its advantages, e.g., rapid prototyping and free design. In aeronautic and astronautic engineering, it is especially attractive to apply AM processing, especially Selective Laser Melting(SLM), into primary structures that always occupy most of the whole mass of aircraft or spacecraft. In this paper, an innovative lattice sandwich structure that is suitable to be manufactured with SLM is adopted to design the typical cylinder under axial compression. Firstly, the mechanical properties of pyramidal lattice are investigated, and the bearing capacity of the lattice sandwich cylinder is given analytically for each failure mode. Secondly, a composite cylinder is re-designed in the form of lattice sandwich structure, which sizes are ultimately obtained through optimization. Finally, finite element model of the innovative cylinder is established and several kinds of imperfection are introduced to simulate the defects caused by SLM. Numerical result shows that the lattice sandwich design can obviously enhance the bearing capacity of cylindrical shell even though the original one is designed with composite material. In other words, SLM has great potential in improving the primary structure of spacecraft in the future.展开更多
Prostate cancer is a clinically heterogeneous disease and remains the most common non-skin malignancy in men worldwide(Abate-Shen and Shen,2000;Litwin and Tan,2017),which is often diagnosed through screening with digi...Prostate cancer is a clinically heterogeneous disease and remains the most common non-skin malignancy in men worldwide(Abate-Shen and Shen,2000;Litwin and Tan,2017),which is often diagnosed through screening with digital rectal examinations and quantitation of serum levels of prostate-specific antigen(PSA).At the morphological aspect,the Gleason scoring system is regarded as the most reliable and predictive histo-logical grading system(Welch and Albertsen,2009;Heidenreich et al.,2011).展开更多
基金supported by the Natural Science Foundation of China(Grant No.11772187)the Natural Science Foundation of Shanghai(Grant No.16ZR1436200)
文摘The placement optimization of piezoelectric actuators and active vibration control of a membrane structure are studied in this paper. The classical linear quadratic regulator con- trollers are designed to suppress the unwanted vibration. Simulation results indicate that the optimal locations of piezoelectric actuators are affected deeply by the additional mass and stiff- ness of actuators, the computational efficiency of particle swarm optimizer is higher than that of genetic algorithm for this particular problem, and the control performance of optimally placed actuators is better than that of non-optimally placed actuators.
基金supported by the National Natural Science Foundation of China (No. 11602147)the National Key Research and Development Program (No. 2017YFB 1102800)
文摘Additive Manufacturing(AM) processing has attracted wide attention due to its advantages, e.g., rapid prototyping and free design. In aeronautic and astronautic engineering, it is especially attractive to apply AM processing, especially Selective Laser Melting(SLM), into primary structures that always occupy most of the whole mass of aircraft or spacecraft. In this paper, an innovative lattice sandwich structure that is suitable to be manufactured with SLM is adopted to design the typical cylinder under axial compression. Firstly, the mechanical properties of pyramidal lattice are investigated, and the bearing capacity of the lattice sandwich cylinder is given analytically for each failure mode. Secondly, a composite cylinder is re-designed in the form of lattice sandwich structure, which sizes are ultimately obtained through optimization. Finally, finite element model of the innovative cylinder is established and several kinds of imperfection are introduced to simulate the defects caused by SLM. Numerical result shows that the lattice sandwich design can obviously enhance the bearing capacity of cylindrical shell even though the original one is designed with composite material. In other words, SLM has great potential in improving the primary structure of spacecraft in the future.
基金This research was supported by the Center for Health Statistics and Information,National Health Commission of China(2127000141).
文摘Prostate cancer is a clinically heterogeneous disease and remains the most common non-skin malignancy in men worldwide(Abate-Shen and Shen,2000;Litwin and Tan,2017),which is often diagnosed through screening with digital rectal examinations and quantitation of serum levels of prostate-specific antigen(PSA).At the morphological aspect,the Gleason scoring system is regarded as the most reliable and predictive histo-logical grading system(Welch and Albertsen,2009;Heidenreich et al.,2011).
