R600a/R23两级自动复叠制冷系统降温特性研究

以R600 a/R23两级自动复叠制冷系统为例,研究了不同配比条件下,制冷系统中的特征点温度在降温过程中变化特性。试验表明混合制冷剂的配比是自动复叠制冷系统关键问题,通过控制关键点的温度可以判断混合制冷剂的最佳配比。     

羧甲基壳聚糖在果蔬保鲜中的应用研究进展

综述了羧甲基壳聚糖的特性及其在果蔬的涂膜保鲜中的应用研究进展,讨论了羧甲基壳聚糖的浓度、分子量、pH值、取代度对其特性的影响,介绍了羧甲基壳聚糖对果蔬的涂膜保鲜效果。本文对开发羧甲基壳聚糖在果蔬防腐保鲜方面的应用具有理论指导意义。     

基于分形动力学过程的腐蚀预测模型

腐蚀是一种复杂随机现象,可以用分形理论更好地描述。本文根据分形动力学过程,以一组基于不同表面条件下的腐蚀发生概率为参数,建立计算机模型来预测大气、土壤环境的金属腐蚀过程。计算结果和实际腐蚀特征吻合一致。此外,本文还讨论了幂函数腐蚀模型中指数n和各种腐蚀概率之间的定量关系,揭示了腐蚀发展规律。     

Characterization of Hamiltonian symmetries and their first integrals

We provide explicit criteria when the Hamiltonian symmetries for a finite dimensional canonical Hamiltonian system correspond to their first integrals. There are two approaches used for the construction of the first integrals once the symmetry is known. In the standard classical approach the first integrals are obtained up to a distinguished function of time t. In the second, which is recent, the integrals are given by a formula which involves the determination of the divergence terms. In both methods utilized, the first integrals are not determined uniquely. Firstly we show what conditions need to be imposed on the Hamiltonian symmetry in order that it constructively and uniquely yields a first integral. Secondly we provide the extra condition on the first integral for the first approach and the integrability conditions on the divergence term for the second. As a consequence, we show that both methods are in fact equivalent. Furthermore, it is shown that when the Hamiltonian symmetries provide first integrals they form a Lie algebra. Moreover, we prove that the Hamilton first integral is invariant under the Hamilton action symmetry. Several examples taken from the literature are given to illustrate our results and conditions.     

盐酸掺杂制备导电性聚苯胺的工艺优化研究

掺杂是获得高导电性聚苯胺的重要手段.本文采用盐酸进行掺杂,通过实验研究了不同条件下盐酸掺杂对聚苯胺基本性能的影响,优化了制备聚苯胺的工艺条件.当过硫酸铵与苯胺比为1时,聚合产率高达66.14%;当盐酸浓度为1.5mol/L时,室温下反应12h导电性最好.制备了聚苯胺样品,并对样品进行了FT-IR、SEM、XRD测试.结果均表明盐酸掺杂聚苯胺的反应主要发生在醌环上,掺杂后聚苯胺有一定的结晶性,且呈微纳米颗粒状、分布均匀,电导率达到1.29S·cm~(-1).正交试验得出的优化工艺为:盐酸浓度为1.0mol·L~(-1),氧化剂与苯胺单体摩尔比为1∶1,室温条件下反应4h.     

Functionally graded coatings on biomaterials: a critical review

Surface coating on biomaterial implants remained a challenging task to researchers because of its simultaneous demand for various properties. Post-surgery problems like aseptic loosening and fibrous tissue encapsulation reduced the life of implants, thus threatening their durability and reliability. However, with the blessing of modern biomaterial science, scientists have coped up the challenge by developing bioactive, graded structure coating on bio-implants. Gradation in composition, structure, and porosity in coating showed a new path of success in this field. Thus, this review paper summarizes different functionally graded bioactive coatings, their deposition techniques, and characteristics to a large extent. It also emphasizes on the thrust area in this field and probable future direction, which can lead us near to success.     

夫琅禾费衍射的光谱特性

基于MATLAB语言,以夫琅禾费衍射为研究对象,数值模拟了夫琅禾费圆孔衍射和单缝衍射光谱特性,通过改变狭缝宽度和入射波的波长,数值模拟得到夫琅禾费单缝衍射的光强变化图和光谱特性图。结果表明,圆孔衍射的光强比单缝衍射的光强曲线在次级明纹的强度更加低,夫琅禾费衍射的结论与实际理论和试验吻合的较好。研究结果为夫琅禾费衍射的研究提供参考。     

三角晶格二维光子晶体的横磁模特性

基于平面波展开法,以介电常数分别为1F/m和12F/m的物质构成三角晶格二维光子晶体,改变空气孔半径r与晶格常数a之间的大小,数值模拟得到了三角晶格二维光子晶体横磁模带隙,当r=.4α时形成三处三角晶格二维光子晶体横磁模的带隙,其中最大三角晶格二维光子晶体横磁模带隙出现在0.6766—0.8000Hz,差值为0.1234Hz。研究结论为光子晶体器件的制作提供参考。     

Stochastic partial differential equations in bounded domains with Dirichlet boundary conditions

In this paper we prove the existence of a unique solution for a class of stochastic parabolic partial differential equations in bounded domains, with Dirichlet boundary conditions. The main tool is an equivalence result, provided by the stochastic characteristics method, between the stochastic equations under investigation and a class of deterministic parabolic equations with moving boundaries, depending on random coefficients. We show the existence of the solution to this last problem, thus providing a solution to the former.     

鸟苷发酵不同阶段发酵液紫外特征光谱的研究

研究了发酵不同阶段鸟苷发酵液的紫外吸收光谱,结果表明,鸟苷发酵不同阶段发酵液紫外吸收光谱会呈现相应的特征光谱。发酵前期除了275nm处的波峰外,在249nm又出现了一个新峰,并且随着发酵时间增加新峰逐渐升高成为主峰;发酵中期275nm处的波峰逐渐减弱并最后消失;发酵后期249nm处的波峰成为发酵液的特征波峰,并随时间的增加逐渐上升;发酵末期的显著特征为发酵液λmax的吸光值基本不变。鸟苷发酵不同阶段发酵液特征光谱研究为人们认识鸟苷发酵的动态过程提供了一种新的技术和途径,对于鸟苷发酵生产具有一定的指导意义。