Theoretical analysis and results of computer simulation show that the proposed method is not only feasible but also simple comparing with classic method . secondly , in connection of hidden danger in security due to symmetric system , a novel encoding techniques is proposed with spherical wave illumination based on asymmetric system 其次,针对现有光学加密系统的对称性给系统安全性能所带来的隐患,在4f系统的基础上,不增加系统元件的情况下,提出了一种用球面波照射非对称准傅立叶变换系统进行光学图像加密的新方法。
Because of the elements which run under nonideal linearity and unentire symmetry in the power system , the loads which are different and change randomly , the methods which adjust and control the system faultily and operate improperly , the disturbance and the malfunction which happen somewhere , the current and voltage in the supply system are distorted seriously and thus large amount of harmonics are produced 但是，由于电力系统元件运行的非理想线性或非完全对称、负载的性质各异且随机变化、调控手段的不完善以及错误操作、外来干扰和各种故障的存在，供电网中的电流(电压)发生畸变，产生大量谐波。
This factory production wind curtain cabinet , exhibits thecabinet , the prepared food cabinet , the fresh meat cabinet , maintainsfreshness the cabinet , the supermarket convenience cabinet , ordersfood the cabinet , the beer cabinet , collection and so on leng gui , island cabinet , cold drinks bar , cold storage maintains freshness , therefrigeration is a body , its control element uses internationally , thedomestic name brand factory production , the chinese and foreign highquality name brand compressor , conforms to the country standingoperating procedure requirement 本厂生产的风幕柜陈列柜熟食柜鲜肉柜保鲜柜超市便利柜，点菜柜啤酒柜冷柜岛柜冷饮柜冷库等集保鲜冷藏为一体，其控制系统元件均采用国际，国内名牌厂家生产，中外优质名牌压缩机，符合国家标准规定要求。
