利用光纤共焦扫描显微镜的轴向响应曲线测定压电陶瓷的逆压电伸缩效应

在光纤共焦扫描显微镜（FOCSM）的基础上,利用其轴向响应曲线的线性部分,给出了一种测定物体微位移的新方法。并用该方法精确测量了压电陶瓷微小的逆压电伸缩效应,分辨率可以达到5nm。     

精密角度传感器及其标定技术的研究

介绍了精密角度传感器和不使用任何精密参考仪器的角度传感器的自标定方法。采用补偿技术制作了一对角度传感器,可以克服光源热漂移带来的影响,并进行了标定。两个角度传感器的测量范围为180″,分辨率分别为0．003″,0．004″。平均灵敏度标定的重复性误差为0．015％,线性误差的标定重复性误差为0．015″。     

Applicability of scalar theory for analysis of mode reflection from an optical dielectric waveguide end

Scalar and vector theories are compared for weakly guided modes reflected from a planar optical dielectric waveguide end or laser facet. By utilizing the free space radiation mode method the range of validity of the scalar theory over a wide range of reflectivities is given explicitly for the first time.     

Contributions of atom probe tomography to the understanding of nickel-based superalloys

Atom probe tomography enables atomic level microstructural characterization to be performed on complex engineering materials such as superalloys. The technique provides information on the size, morphology and compositions of coexisting phases, the solute partitioning of the elements between the phases, and solute segregation to interfaces and grain boundaries. This information leads to a more complete understanding of nickel-based superalloys. The types of atomic level information that may be obtained with atom probe tomography are illustrated with examples of the formation of fine γ precipitates within the central region of the γ′ phase in PW 1480, the evolution of the dual γ′/γ″ nature of secondary precipitates in alloy 718, the interphase precipitation of the γ′ phase at the primary γ″–γ interface in alloy 718, and the quantification of the level and spatial extent of the boron segregation at grain boundaries in a nickel–molybdenum superalloy.     

Signal Processing Scheme for Increasing System Resolution in Determination of the Scattering Position in an OCT System

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放射诊断学史上新的里程碑—电子计算机X射线断层成像（CT）

通过对电子计算机X射线断层成像（CT）技术的发明过程的描述,展现了科学发明在交叉学科取得重大成就的典型范例,对科学研究将产生有益的启示。     

超声成像实验仪

我们模拟了一个原理相对容易、结构相对简单的超声成像实验。通过超声波测试仪发射和接收换能器信号 ,输出的电压信号送入计算机的A/D卡。A/D卡的另一通道采集换能器的跃变位置信息 ,并将数据提供给成像程序 ,把物体某一断层的截面图画出。通过这一实验 ,我们可以了解超声波在固 /液两相流中的传播原理 ,同时也可掌握数据采集和一般的成像方法     

A “ladder” Morphology in an ABC Triblock Copolymer

ABC triblock copolymers are known to exhibit a wide variety of unique types of morphologies compared to AB diblock copolymers. In the present study, poly(styrene-block-(ethylene-alt-propylene)-block-(methyl methacrylate)) (SEPM) triblock copolymers were synthesized and their morphologies were extensively studied by transmission electron microtomography (TEMT). In the SEPM triblock copolymer, two kinds of morphologies coexist: One was the well-known knitting morphology, and the other was a novel morphology called the “ladder morphology”. The ladder morphology was a major morphology in the SEPM copolymer, the stability of which was discussed in terms of the interfacial area and the solubility parameters between the three components.     

光谱法分析迭代重建过程中的滤波

应用光谱法讨论了滤波器及其滤波方案对重建效果的影响。数值模拟重建场,应用光谱法分析了1/4,1/5,1/8均值滤波器,1/5中值滤波器,1/3行、列滤波器,在内嵌、外置等情况下对代数迭代重建的场滤波效果的影响。结果发现：用代数迭代法重建的场含有较大噪声,需要平滑处理;采用1/4,1/5或1/8均值滤波器仅对迭代结果滤波,会严重降低重建精度;采用1/4,1/8均值滤波器内嵌在迭代过程中按一定的迭代次数滤波,可以在一定程度上改善重建精度;采用1/5中值滤波器内嵌在迭代过程中比相应的均值滤波器重建效果更好;内嵌1/5中值滤波器和均值滤波器交替滤波,效果比单一的滤波器滤波更好。采用不同的滤波器和滤波方案对重建结果的影响差别较大。     

光谱法分析场频对重建精度的影响

数值模拟重建场,采用光谱法讨论了场的属性,尤其频率对重建精度的影响。用Gauss函数建立了双峰模型场,并对其进行了Fourier频谱分析。使用代数迭代法对模型场进行了重建,并对重建场进行了误差分析,结果发现重建场的峰分布、方向和形状都与原场相似,但峰高有所下降,边界出现波动。文章认为出现这种现象的主要原因是滤波造成的,并通过改变Gauss函数的收敛因子来改变场频,采用数值分析方法对这一观点进行论证,结果证明该观点是正确的。同时发现,边界对重建精度影响较大,边界为零的近似误差增大时,重建精度下降,甚至导致迭代不收敛。所以应用代数迭代重建场时,必须注意边界为零的条件。