In consideration of the problem that the effect of conduit structure on water hammer has been ignored in the classical theory,the Poisson coupling between the fluid and the pipeline was studied and a fourteen-equation...In consideration of the problem that the effect of conduit structure on water hammer has been ignored in the classical theory,the Poisson coupling between the fluid and the pipeline was studied and a fourteen-equation mathematical model of fluid-structure interaction(FSI)was developed.Then,the transfer matrix method(TMM)was used to calculate the modal frequency,modal shape and frequency response.The results were compared with that in experiment to verify the correctness of the TMM and the results show that the fluid-structure coupling has a greater impact on the modal frequencies than the modal shape.Finally,the influence on the response spectrum of different damping ratios was studied and the results show that the natural frequency under different damping ratios has changed little but there is a big difference for the pressure spectrum.With the decreasing of damping ratio,the damping of the system on frequency spectrum is more and more significant and the dispersion and dissipation is more and more apparent.Therefore the appropriate damping ratio should be selected to minimize the effects of the vibration of the FSI.The results provide references for the theory research of FSI in the transient process.展开更多
文摘In consideration of the problem that the effect of conduit structure on water hammer has been ignored in the classical theory,the Poisson coupling between the fluid and the pipeline was studied and a fourteen-equation mathematical model of fluid-structure interaction(FSI)was developed.Then,the transfer matrix method(TMM)was used to calculate the modal frequency,modal shape and frequency response.The results were compared with that in experiment to verify the correctness of the TMM and the results show that the fluid-structure coupling has a greater impact on the modal frequencies than the modal shape.Finally,the influence on the response spectrum of different damping ratios was studied and the results show that the natural frequency under different damping ratios has changed little but there is a big difference for the pressure spectrum.With the decreasing of damping ratio,the damping of the system on frequency spectrum is more and more significant and the dispersion and dissipation is more and more apparent.Therefore the appropriate damping ratio should be selected to minimize the effects of the vibration of the FSI.The results provide references for the theory research of FSI in the transient process.
文摘同态加密(homomorphic encryption,HE)由于低执行效率和无法保护数据完整性的问题严重限制了其在实际应用中的部署,尤其是在对延迟有严格要求的场景中,为此,提出了一种新的HE来解决这些问题并增强通用性.为了解决执行效率低的问题,设计了多线程矩阵乘法(multithreaded matrix multiplication,MMM)算法.利用MMM算法,可以将加密任务拆解分配给多个线程并行执行,达到加速的目的.针对恶意服务器场景下的数据篡改问题,设计了一个可验证加密机制,利用非交互零知识证明(zk-SNARK)技术保护外包计算中密文的完整性.结合MMM算法,设计了一种高效的基于零知识证明的可验证全同态加密算法(verifiable fully homomorphic encryption based on zk-SNARKs,zk-VFHE).理论分析和实验结果表明,zk-VFHE比同类协议具有更快的执行速度和更高的安全性.
