通过研究OFDM(orthogonal frequency division multiplexing)系统的定时同步算法和信道估计算法,综合考虑算法性能和算法的计算量,提出适合FPGA实现的定时同步和信道估计算法,实现了基于IEEE802.16d协议的OFDM基带系统的FPGA设计。基于ISE和Modelsim软件,对所设计的系统进行综合和仿真,在XILINX公司的XC2VP30芯片上实现了接收机和发射机。发射机和接收机的各级间全部采用流水线结构,综合和仿真结果表明所设计系统节省了硬件资源,提高了数据传输速率。
Converting ambient vibration energy into electrical energy by using piezoelectric energy harvester has attracted a lot of interest in the past few years.In this paper,a topology optimization based method is applied to simultaneously determine the optimal layout of the piezoelectric energy harvesting devices and the optimal position of the mass loading.The objective function is to maximize the energy harvesting performance over a range of vibration frequencies.Pseudo excitation method (PEM) is adopted to analyze structural stationary random responses,and sensitivity analysis is then performed by using the adjoint method.Numerical examples are presented to demonstrate the validity of the proposed approach.
