巡游电子系统中电子-声子相互作用对磁性激发的影响

从Ｐｅｉｅｔｌｓ－Ｈｕｂｂａｒｄ哈密顿量出发，讨论了电子－声子相互作用对巡游电子系统磁性激发的影响。结果表明，电子－声子相互作用，不仅改变了Ｘ^－＋（ｑ，ω）的动力学特性，而且在系统能带结构中，使两个自旋子带分裂减小，从而更有利于电子－空穴对的个别激发；另一方面，电－声子相互作用导致自旋波激发出现能隙。     

单粒子束细胞定位照射装置中微图像处理系统的设计

为了适应细胞辐射生物学基础研究的需要 ,按照生物实验的要求和装置的物理指标设计了实验室单粒子束装置的微图像处理系统。设计中遵循了科学性和经济性的原则 ,结构紧凑 ,性能稳定。结果表明 ,该系统达到了预期指标 ,解决了单粒子束装置精确定位辐射的这一关键技术 ,为细胞核的辐射实验提供了有力的工具     

用好三"比"化难为易

物理教学的艺术贵在变抽象为具体，澄模糊为清晰，化平淡为生动，转深奥为浅显．而用好三“比”——对比、类比和比喻则是提高教学艺术水平的重要途径．通过活用三“比”来创设教学情境，激发学生兴趣，培养学生能力，可达到四两拨千斤之效，收到事半功倍之果．     

Controlling Spiral Dynamics in Excitable Media by a Weakly Localized Pacing

Spiral dynamics controlled by a weakly localized pacing around the spiral tip is investigated. Numerical simulations show two distinct characteristics when the pacing is applied with the weak amplitude for suitable frequencies： for a rigidly .rotating spiral, a transition from rigid rotation to meandering motion is observed, and for unstable spiral waves, spiral breakup can be prevented. Successfully preventing spiral breakup is relevant to the modulation of the tip trajectory induced by a localized pacing.     

原位聚合法制备超疏水的聚乙烯纳米复合材料

采用一种新方法将Ziegler-Natta催化剂组分TiCl4和MgCl2负载到蒙脱土(MMT)的层间,制备了TiCl4/MgCl2/MMT插层型催化剂.利用Ziegler-Natta催化剂特有的"形态复制效应",通过乙烯原位聚合制备出了表面具有花瓣状形态的聚乙烯纳米复合材料.这种聚乙烯纳米复合材料的表面与水的接触角达到(152.2±0.8)°,呈现超疏水性质.     

基于多参数融合的红外光谱对混合物的组分识别研究

为解决混合物组分的识别问题,该文以7种标准品以及由7种标准品配制的26种混合物为研究对象,以准确率与误判率为混合组分识别效果的评价指标,在研究谱峰匹配算法、非负最小二乘匹配算法与相关系数匹配系数算法的基础上,采用一种基于多特征融合的BP神经网络模型红外光谱技术对混合物组分进行识别,并与逻辑回归模型进行了对比。结果表明,3种单一匹配算法的识别准确率均低于76.31%,多特征融合的逻辑回归模型与多特征融合的BP神经网络模型预测集的识别准确率分别为83.33%和98.18%,误判率分别为4.76%和1.82%。研究结果表明,中红外光谱技术结合BP神经网络模型可以更好地进行混合物的组分识别。为了进一步探究模型对混合组分最低浓度的检测能力,采用香兰素和乙醇两组分溶液进行检出限的研究。结果表明混合物中香兰素的质量浓度为0.03 g/mL时准确率为100.00%,误判率为14.29%;香兰素质量浓度低于0.03 g/mL时,准确率下降20.00%,误判率上升19.04%。故可认为该研究能识别出的香兰素乙醇溶液中香兰素的最低质量浓度为0.03 g/mL。     

非结构网格变形方法研究进展

动网格技术中的非结构网格变形是计算流体力学和计算固体力学的关键技术之一.本文在总结现有非结构网格变形方法的基础上, 提出了一种网格变形方法的详细分类, 将现有方法归类为虚拟结构法、偏微分方程法和代数法. 本文综述了各类方法的最新研究进展, 分析并比较了各类方法的特性, 评述了当前网格变形研究的几个主要方向:复杂结构外形在不规则变形下的动网格生成、三维动网格生成、并行动网格生成和动节点技术. 最后简要地探讨了该领域的发展趋势.      

列车荷载下海相沉积软土循环累积变形研究

以宁波轨道交通1号线②、③和④层海相沉积软土为对象,进行GDS单向振动三轴试验,研究了不同动应力幅值和频率作用下软土的动力学特性.结果表明：动力幅值越大,循环累积塑性变形越大,动应力的幅值大小对累积塑性变形有较明显的影响;在动应力为12kPa时,④层粘土的累积塑性应变比相同条件下②层和③层土的应变大;在相同动应力幅值时,②和④层土随频率增大,③层土则相反.最后,利用修正的指数模型对循环加载累积塑性应变的变化进行拟合,并得到了优化的模型参数.     

Quantum critical behavior in an antiferromagnetic heavy-fermion Kondo lattice system(Ce_(1-x)La_x)_2Ir_3Ge_5

The measurements on temperature dependences of magnetic susceptibility χ(T), specific heat C(T), and electrical resistivity ρ(T) were carried out for the antiferromagnetic(AFM)(Ce_(1-x)La_x)_2Ir_3Ge_5(0 ≤ x ≤ 0.66) system. It was found that the Neel temperature TNdecreases with increasing La content x, and reaches 0 K near a critical content xcr =0.6. A new phase diagram was constructed based on these measurements. A non-Fermi liquid behavior in ρ(T) and a log T relationship in C(T) were found in the samples near xcr, indicating them to be near an AFM quantum critical point(QCP) with strong spin fluctuation. Our finding indicates that(Ce_(1-x)La_x)_2Ir_3Ge_5 may be a new platform to search for unconventional superconductivity.     

Improved photovoltaic effects in Mn-doped BiFeO_3 ferroelectric thin films through band gap engineering

As a low-bandgap ferroelectric material, BiFeO_3 has gained wide attention for the potential photovoltaic applications,since its photovoltaic effect in visible light range was reported in 2009. In the present work, Bi(Fe, Mn)O_3thin films are fabricated by pulsed laser deposition method, and the effects of Mn doping on the microstructure, optical, leakage,ferroelectric and photovoltaic characteristics of Bi(Fe, Mn)O_3 thin films are systematically investigated. The x-ray diffraction data indicate that Bi(Fe, Mn)O_3 thin films each have a rhombohedrally distorted perovskite structure. From the light absorption results, it follows that the band gap of Bi(Fe, Mn)O_3 thin films can be tuned by doping different amounts of Mn content. More importantly, photovoltaic measurement demonstrates that the short-circuit photocurrent density and the open-circuit voltage can both be remarkably improved through doping an appropriate amount of Mn content, leading to the fascinating fact that the maximum power output of ITO/BiFe_(0.7)Mn_(0.3)O_3/Nb-STO capacitor is about 175 times higher than that of ITO/BiFeO_3/Nb-STO capacitor. The improvement of photovoltaic response in Bi(Fe, Mn)O_3 thin film can be reasonably explained as being due to absorbing more visible light through bandgap engineering and maintaining the ferroelectric property at the same time.