Fast Generation of GHZ States with Bose–Einstein Condensate in a Cavity

It is shown that strong coupling of Bose–Einstein condensates to an optical cavity can be realized experimentally. With an additional driven microwave field, we show that a highly nonlinear coupling among atoms in a Bose–Einstein condensate can be induced with the assistance of the cavity mode. With such interaction, we can investigate the generation of many body entangled states. In particularly, we show that multipartite entangled GHZ states can be obtained in such architecture with current available techniques.     

基于复小波包分形理论的爬壁机器人故障检测

通过研究爬壁式机器人的控制和运动特征，提出一种基于复小波包分形理论的故障检测方法．利用复小波包的平移不变性，将爬壁式机器人传感器输出信号分解成独立的频谱，并进行阀值处理和重构，从而有效去除高频噪音并提取故障的特征频率；依据信号分形维数的多尺度不变性，在嵌入维数空间，采用维数最大距离法，确定复小波包域故障信号的关联雏数．仿真实验表明，爬壁式机器人在各种异常工作模式下的故障信号关联维数能比较真实地反映其故障状态空间，同时也验证了故障信号的关联维数低于正常信号的关联维数作为故障发生与否的定量判据的正确性．     

Dissimilar autogenous full penetration welding of superalloy K418 and 42CrMo steel by a high power CW Nd:YAG laser

Experiments of autogenous laser full penetration welding between dissimilar cast Ni-based superalloy K418 and alloy steel 42CrMo flat plates with 3.5 mm thickness were conducted using a 3 kW continuous wave (CW) Nd:YAG laser. The influences of laser welding velocity, flow rate of side-blow shielding gas, defocusing distance were investigated. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness and tensile strength testing. Results show that high quality full penetration laser-welded joint can be obtained by optimizing the welding velocity, flow rate of shielding gas and defocusing distance. The laser-welded seam have non-equilibrium solidified microstructures consisting of γ-FeCr_0.29Ni_0.16C_0.06 austenite solid solution dendrites as the dominant and very small amount of super-fine dispersed Ni₃Al γ′ phase and Laves particles as well as MC needle-like carbides distributed in the interdendritic regions. Although the microhardness of the laser-welded seam was lower than that of the base metal, the strength of the joint was equal to that of the base metal and the fracture mechanism showed fine ductility.     

磁共振碳谱研究:应用分子子图指数估计与预测卤代烃化学位移

系统研究了核磁共振碳谱(¹³C NMR)与化学位移规律及其定量构谱关系(QSSR).本文提出了一组含多元素组成的分子子图指数矢量(VMSG),并发现它与卤代烃化学位移(CSRX)有很好线性相关性.采用多元线性回归(MVLR)进行准确估计与预测,结果良好.     

环F_p+uF_p+vF_p上循环码

本文讨论了有限非链环R=Fp+uFp+vFp上的循环码.通过环R上的循环码与多项式环Rn=(Fp+uFp+vFp)[x]/(xn-1)的理想的对应关系给出了R上循环码的刻画.最后定义了一个Gray映射,并刻画了R上的循环码在该映射下的像.     

紧凸空间中一类非连续博弈纳什均衡的存在性

利用单位划分原理和Browder不动点定理,在对博弈局中人收益函数没有做任何连续性假设条件下,讨论了一类非空、紧凸空间上博弈纳什均衡存在性问题。当局中人的最优反应函数满足一些基本条件时,得到了若干纳什均衡存在性定理,是对现有讨论纳什均衡存在性问题的一个重要拓展和完善。     

调强放射治疗子野权重优化方法研究

由于子野分割带来的误差, 使得调强放疗(Intensity Modulated Radiation Therapy, 简称IMRT)计划系统所制作的计划往往不能满足临床要求。 本研究将采用基于共轭梯度法的子野权重优化方法来减小此误差, 提高制作计划的效率和效果。 采用共轭梯度法优化子野权重和微调子野形状, 最终使得子野分割前后强度误差最小。 在精确放疗系统中对常见的临床病例（鼻咽癌和周围性肺癌）进行测试, 通过对比靶区和危及器官的剂量体积直方图以及CT片上的等剂量线, 发现子野权重优化后靶区的平均剂量分别从87.0%提高到100.2%和从90.0%提高到98.4%, 更好地满足临床要求。