两类半隐式随机Runge-Kutta方法

本文针对一般的Ito随机微分方程,应用彩色树理论构造了两类稳定性较好的强1阶半隐式Runge-Kutta(RK)方法,数值实验证明了所得方法的精度和有效性.     

A clutter rejection method for color flow imaging using projection-pursuit algorithm

A clutter rejection method based on the projection-pursuit （PP） was proposed to reduce velocity artifacts caused by clutter signals in the ultrasound color flow imaging （CFI）. Principal components are extracted by the PP to reduce their sensitivity to strong clutter signals originating from non-blood-flow regions. Then blood signals are obtained by removing the estimated clutter space in the eigenvector domain. Computer simulations and in vivo experiments are carried out to validate the proposed method. Results show that compared with conventional high-pass filter （HPF）, this method can achieve a better velocity profile and vessel shape. It is also shown that this method causes less velocity artifacts in non-blood-flow regions than the eigenvector filter and achieves a higher inside-to-outside blood energy ratio by 5 dB. Therefore, this approach is expected to be an effective clutter rejection algorithm to improve the image quality in the ultrasound CFI.     

Influence of Aging Time on the Properties of Precursors of CuO／ZnO Catalysts for Methanol Synthesis

The aging process of pure copper precursors and copper-zinc binary precursors were studied by XRD, TG-DTG and TPR techniques. The catalytic activity and stability of CuO/ZnO were tested using fixed-bed flow reactor, and the physical properties of the catalysts and Cu species were characterized with N2 adsorption and N2O passivation method, respectively. For the Cu-Zn binary system prepared at the precipitating condition of pH=8.0 and temperature=80℃, the initial phase was a mixture of copper nitrate hydroxide Cu2(NO3)(OH)3, georgeite and hydrozincite Zn5(CO3)2(OH)6. By increasing the duration of its aging time, the phase of Cu2(NO3)(OH)2 first transited to georgeite, and then interdiffused into Zns(CO3)2(OH)6 and resulted in two new phases: rosasite (Cu,Zn)2CO3(OH)2 and aurichalcite (Zn,Cu)5(CO3)2(OH)6. The former phase was much easier to be formed than the latter one, while the latter phase was more responsible for the activity of methanol synthesis than the former one. It is found that the composition and structure of the precursors altered obviously after the colour transition point. The experimental results showed that methanol synthesis is a structure-sensitive catalytic reaction.     

图象的灰度一彩色连续变换处理

本文提出一种灰度-彩色连续变换的伪彩色图象处理方法。此法把连续的灰度级变换到CIE空间的一条连续的彩色带,从而避免了一般彩色处理中的伪轮廓和有害噪音,可以广泛应用于各种图象的伪彩色处理。     

品红甲亚胺染料影像光稳定性的研究 Ⅱ.抗氧化剂猝灭单重态氧的反应速率常数测定

本文利用高效液相色谱法测定了色满类,双螺色满类,对一甲氧基苯酚类和双螺茚类抗氧化剂与单重态氧反应的物理猝灭速率常数和化学猝灭速率常数。实验结果表明,抗氧化剂猝灭单重态氧的过程以物理猝灭为主,物理猝灭速率常数和总猝灭速率常数愈大,品红甲亚胺染料的防褪色效果愈好,但存在一极限褪色率。     

金属离子对彩色成像过程的影响

通过测量和计算彩色单层片中成色剂的照相活性、偶合效率以及漂白前银密度等参数,研究了在分散四当量成色剂青(Ⅰ)时掺入金属离子Mg²⁺、Zn²⁺、Fe³⁺和Cu²⁺对彩色青单层片的成像过程中各个化学反应的影响。本实验的结果表明,成色剂中加入的金属离子Cu²⁺和Fe³⁺对成像过程的初始反应中的Ag影像形成产生不利的影响,但它们能促进偶合过程中青(Ⅰ)与显影剂氧化产物作用所生成的隐色体转变成染料的速率。Mg²⁺和Zn²⁺的加入主要是对偶合过程中青(Ⅰ)的偶合效率产生不利的影响。上述原因的综合影响,最终降低了彩色单层片的感光度。     

亚硫酸盐对彩色成像过程的影响

研究了彩色显影液中亚硫酸钠对含内偶青成色剂的卤化银单层片的彩色成像过程的各化学反应、青染料影像的有害吸收以及染料云形态的影响,结果表明亚硫酸钠能(1)提高银影像的形成速度;(2)降低成色剂的表观偶合效率;(3)增加青染料影像的有害吸收;(4)使染料云缩小并且使染料云的分布变窄。     

彩色影像形成的电化学研究

使用成色显影的彩色感光材料中,构成彩色影像的单元是围绕在被显影的卤化银颗粒上所生成的染料云,为深入了解彩色影像的结构和改善彩色影像质量,研究染料云的形态很有意义,照相乳剂中卤化银的颗粒很小,很难用各种显微镜观察染料云的形态,本文采用电化学方法,用表面涂以成色剂胶冻的金电极作为工作电极。     

数字滤波法再现电子全息图

在分析电子全息图特性的基础上，提出频谱滤波法对电子全息图进行数字再现，以解决其再像之间相互重叠的问题，此方法首先将数字化的电子全息图进行傅里叶变换得到全息图的空间频谱，然后对此频谱进行滤波处理并作反傅里叶变换得到一幅新的全息图，最后再用一般的数字再现法对此新的全息图进行再现，用这种方法，可以很方便地得到不受干扰的再现实像。     

明胶层中的扩散和反应动力学研究Ⅵ.球型扩散及扩散伴随一级反应过程的数值解

本文采用有限差分法导出了扩散物从空间一点向周围作三维球型扩散和边扩散边进行一级反应的动力学方程的数值解,并描述了其求解方法。在相同的参数下,获得的数值解与相近边界条件的分析解结果对照,一致性良好,为进而研究染料云的形成过程打下基础。