Symmetrical Fundamental Tensors, Differential Operators, and Integral Theorems in Differential Geometry

To make the geometrical basis for soft matters with curved surfaces such as biomembranes as simple as possible, a symmetrical analytical system was developed in conventional differential geometry. The conventional second fundamental tensor is replaced by the so-called conjugate fundamental tensor. Because the differential properties of the conjugate fundamental tensor and the first fundamental tensor are symmetrical, the symmetrical analytical system including the symmetrical differential operators, symmetrical differential characteristics, and symmetrical integral theorems for tensor fields defined on curved surfaces can be constructed. From the symmetrical analytical system, the symmetrical integral theorems for mean curvature and Gauss curvature, with which the symmetrical Minkowski integral formulas are easily deduced just as special cases, can be derived. The applications of this symmetrical analytical system to biology not only display its simplicity and beauty, but also show its powers in depicting the symmetrical patterns of networks of biomembrane nanotubes. All these symmetrical patterns in soft matters should be just the reasonable and natural results of the symmetrical analytical system.     

Ag在Si表面吸附的第一性原理研究

采用基于密度泛函理论的第一性原理平面波赝势方法计算优化了Ag原子在硅惯习面Si(111)和Si（220）晶面的最佳吸附位置,并计算了Ag/Si(111)和Ag/Si(220)体系的表面吸附能和表面态电子结构．研究表明:Si基表面Ag原子的最稳定吸附居于Si(220)晶面的穴位,此时的吸附能最低,其值为5.2569eV,属于强化学吸附;同时由于在Ag/Si(220)体系中,Ag-4d轨道和表面态Si-3s、3p轨道电子的强相互作用,以及Ag-4p轨道的电子云强偏向于Si-3s、3p轨道使得体系的能隙宽度变窄,导电性急剧增大．     

圆孔与三极子组合单元频率选择表面研究

应用谱域法分析了圆孔与三极子组合单元频率选择表面(FSS)的频率响应特性。分析了组合单元的结构参数、电磁波极化和入射角度对其稳定性的影响。研究结果表明,该组合单元的频率响应特性曲线具有明显的两个阻带和一个通带,且具有良好的极化稳定性和角度稳定性。在结构参数中,圆孔大小对频率响应特性曲线的位置影响较大,极子长度对传输带宽影响较大,而极子宽度影响较小。通过单元结构参数调整,可获得良好的宽带传输和陡峭下降边缘特性,实现相临波段信号分离和多波段通讯。该结构FSS可应用于卫星通讯、雷达罩及其他相关领域。     

类毛线团表面银微球的制备及其表面增强拉曼散射性能研究

以低分子量聚丙烯酰胺（PAM）为模板,通过液相化学还原法首次制备了类毛线团表面银微球,并采用扫描电子显微镜（SEM）、X射线衍射（XRD）及氮气吸附法对银微球形貌及分散性进行表征。结果表明,微球是由纳米片有序组装而成的介孔材料,表面遍布棱角和狭缝。考察了PAM分子量、硝酸银浓度及还原体系pH值变化对银球结构的影响,并对类毛线团表面的形成过程进行了阐述。将银球用作表面增强拉曼散射（SERS）检测基底,可显著地增强罗丹明B（Rh B）分子的拉曼信号强度,能够检测出浓度低至10^-16mol/L的Rh B。     

材料表面可逆润湿性行为研究进展

 综述了近几年制备可逆润湿性表面的常用方法及常见的控制润湿性可逆变换的手段,例如在原材料表面添加光敏性物质、热响应性物质及pH敏感性物质等,并介绍了其响应性机理;总结了目前尚不能形成规模化生产、性能不稳定等研究薄弱点;展望了未来研究方向及具有可逆润湿性生物质材料前景,认为后续研究的重点亦可放在性能稳定性等方面。     

木材表面原位生长WO3纳米片及其光响应行为

 采用乙醇作为诱导剂,利用简单的低温水热合成法在木材表面原位生长无机WO₃纳米片,探讨WO₃/木材的光响应功能。使用扫描电镜（SEM）、X射线衍射（XRD）、紫外-可见光（UV-vis）、色差仪和热重分析（TG）分别表征了此复合材料形貌、相结构、紫外光吸收、光响应和热稳定性能,并进一步探讨了此复合材料的疏水功能。SEM表明WO₃纳米片均匀的生长在木材表面;XRD表明WO₃具有六方晶相结构;UV-vis表明WO₃处理后的木材与素材相比,其最大吸收波长出现蓝移;光响应测试表明,WO₃/木材在紫外光照射下具有明显的变色功能;TG表明WO₃涂层对木材成分降解起到一定的抑制作用。此外,经过十八烷基三氯硅烷改良后,此复合材料具有超疏水功能。     

Copper foils with gradient structure in thickness direction and different roughnesses on two surfaces fabricated by double rolling

Copper foils with gradient structure in thickness direction and different roughnesses on two surfaces were fabricated by double rolling. The two surface morphologies of double-rolled copper foils are quite different, and the surface roughness values are 61 and 1095 nm, respectively. The roughness value of matt surface can meet the requirement for bonding the resin matrix with copper foils used for flexible printed circuit boards, thus may omit traditional roughening treatment; the microstructure of double-rolled copper foils demonstrates an obviously asymmetric gradient feature. From bright surface to matt surface in thickness direction, the average grain size first increases from 2.3 to 7.4 μm and then decreases to 3.6 μm; compared with conventional rolled copper foils, the double-rolled copper foils exhibit a remarkably increased bending fatigue life, and the increased range is about 16.2%.     

桁架式可展开天线反射面精度试验

为了验证一种桁架式可展开天线结构设计方法的正确性,制作了一个口径为2 m的天线模型,设计了由上部中心立柱加三支杆悬挂支撑天线的试验悬挂方案,用基于PhotoModeler软件建立的摄像测量系统对天线抛物面反射面进行精度测量,将测量数据带入基于浅壳理论推导出的精度计算方程计算反射面误差.模型的反射面精度与设计值接近,表明该结构设计方法适合于设计更大口径的该类型天线.设计制作了6 m×2.8 m口径的天线,并对此天线进行了两种姿态下的展开精度试验,精度测量结果表明反射面精度符合设计要求.     

采用图像轮廓的弹性连接体三维建模与运动估计

为了用较少的参数反映人肢体皮肤的变形,该文提出以旋转圆锥曲面进行弹性连接体(人体)三维建模.模型包括人体三维骨架和代表人肢体皮肤的变形曲面方程,每个肢体只需调整2个变形参数就能反映出人肢体皮肤的变形.根据双目图像序列的轮廓估计人体变形和运动参数,包括骨架的运动参数估计和变形曲面的变形参数确定.实验结果表明:该模型能正确地反映人肢体皮肤的变形,运动估计算法能精确地估计人体运动参数.