Field measurement for superconducting magnets of ADS injector Ⅰ

A superconducting magnet prototype for Accelerator Driven Sub-critical System Injection-Ⅰ had been designed and fabricated, and tested in a new made vertical Dewar in November 2012. Batch magnet production was processed after some major revision from the magnet prototype, they include: removing off the perm-alloy shield, extending the iron yoke, using thin superconducting wire, etc. The first one of the batch magnets was tested in the vertical Dewar at the Harbin Institute of Technologyin in September 2013. A field measurement was carried out at the same time by the measurement platform that was seated on the top of the vertical Dewar,the measurement results met the design requirements. This paper will present the field measurement system design, measurement results and discussion on the residual field from the persistent current effect.     

基于混沌序列的双重变换域半脆弱水印算法

提出了一种DCT域与DWT域相结合的半脆弱数字水印算法．该算法设计了三个混沌密钥，在DCT域使用混沌序列生成水印并定义其嵌入位置，在DWT域的高频子带中嵌入水印．水印的嵌入强度能够根据小波系数和人眼的视觉门限自适应的进行调整，可以达到最佳嵌入调制．实验结果表明该半脆弱水印算法具有较佳的篡改区域指示性能，能有效进行数字图像的真实性和完整性鉴定，并且能够区分JPEG压缩与恶意篡改．