强力振荡器栅漏电阻的最佳调变方法

本文叙述一种简单的实验指示方法,用以测定强力振盪器的最佳漏电阻。关于激发比率对板极效率的关系,和Colpitts线路中漏电阻的适当接法等问题,本文亦曾加以讨论。     

CONFORMATION AND CHAIN PACKING STRUCTURES OF POLY (ρ-PHENYLEN BENZOBISTHIAZOLE) BY MOLECULAR SIMULATION*

The conformation, the chain packing stabilization and the unit cell modeling of poly(p-phenylene benzobisthiazole) have been investigated by using molecular simulation techniquein the present work. A coupling behaviour of σ-bond rotations at either side of the pheny-lene ring or the heterocyclic ring was found surely to exceed a length of the repeat unit ofthe polymer chain. For a single chain model, the stable torsion angle of the repeat resultedat 14°. In the crystalline cell minimization, the dihedral angle along the polymer chaincould even be stabilized in various values. It therefore indicates that the intermolecularinteraction does play a considerable role for this polymer forming the conformation. Ac-cording to cohesive energies calculated for these unit cell models, the torsion angle in themost stable crystalline cell is 0°. When the chains packing together, there exist so manyenergy stable wells along the chain axis 0.35--0.36nm apart from neighbouring chains.Most of the unit cells have quite closed cohesive energies. These factors thus cause thedifficulty of forming an unique perfect crystalline structure of the polymer. The presentstudy suggested a number of reasonable unit cells, and the most stable crystalline structurefor this polymer that is monoclinic, non-primitive unit cell.     

Synthesis and Characterization of Small Band-gap Conjugated Polymers - Poly(pyrrolyl methines)

A kind of small band-gap conjugated polymers-poly (pyrrolyl methines) and their precursors-(poly pyrrolyl methanes) have been synthesized by a simple method and characterized by 1HNMR, FT-IR, TGA and UV-Vis. These polymers can be dissolved in high polar solvents such as DMSO, DMF or NMP. The results reveals that the band-gap of the synthesized conjugated polymers are in the range of 0.96～1.14 eV and they all belong to the small band-gap polymers. The conductivity of doped products with iodine is in the range of semiconductor.     

含有50原子%Zn的Ag-Au-Zn合金的研究

合金AgAuZn₂具有一个与郝斯勒合金同晶型结构的β″相,这个β″相存在于一个相当广阔的成分范围里。事实上,β″相就是β′有序结构的超结构。伴随着,β″结构的形成晶格发生突然的收缩。关于Ag-Au替换对于原子分布的影响,也作了系统的观察。在Ag-Au替换过程中,Au和Ag的替换或多或少是无规律性的,但Zn原子则仍保持它们的适宜位置,而不受到影响。当成分偏离于理想化学式AgAuZn₂时,有序度的减小不仅仅是由于化学成分的乖异,而且Ag-An替换也产生了一些无序的排列。高温观察的结果指出:Ag多合金的β′-β转变温度随着Au含量的增加而升高,而β相只能在高温度存在。少量的Au大大地提高了由淬炼而得到的β′相的稳定度。但是Au多的合金无论是在室温和高温都是具有β′结构的。     

银锌合金中的β相变

Owen与Edmunds曾经指出:银锌合金Ag-Zn由β相区骤冷后得到有序的体心立方结构β′相;缓冷则得到六角晶系ζ相;但在β相区进行高温观察,则只得无序的体心立方结构β相(图1)。然而对于相变机构及超结构β′相的性质他们并未说明。     

利用红外吸收积分强度进行碳氢化合物中的族分析

本文对于利用红外吸收光谱的积分强度来进行碳氢化合物的族分析作了初步尝试。从分析原子团CH₂及CH₃的结果来看,这方法是可以利用的。     

利用电子束浮区区熔法制备钼单晶体

本文简单介绍自制的1.5千瓦电子束浮区区熔装置及其工作情况。应用这种装置我们制备了直径4毫米、长2—5厘米的钼单晶体,并掌握了制备定向单晶体的实验技术。制备的钼单晶体没有择优取向;显微镜观察发现晶体表面有大量的台阶(高度在2.3×10^-5—6.3×10^-4厘米),初步推断为蒸发台阶。关键词：     

平面方格及立方格中AB型超格之理论

本文应用王氏之理论於平面方格及立方格中AB型超格。所有计算皆作到第二次近似值,惟仅考虑到邻近原子间之相互作用。所计算者有临界温度与合金成分之关系,秩序之程度,内能,及比热。凡Bethe氏曾经计算过者与本文计算结果相较,均相差无几。     

Unsteady Simulation of a Jet-in-crossflow

The present work represents the first attempt at studying the unsteadiness of jet-in-crossflows using the Reynolds-Averaged Navier-Stokes (RANS) equations. In the past, numerical studies of jet-in-crossflows, with the exception of the few attempts of DNS and LES. are always carried out under the assumption that the flowfield is steady and symmetric about the jet center plane. Growing experimental evidence suggests that this flow is unsteady and periodic. The present work verified the existence of periodicity in jet-in-crossflows numerically. The numerically predicted Slrouhal number is in good agreement with experimental observations. In addition, the present simulation of the jet-in-crossflow were able to resolve the details of flow structures such as the oscillating wake structures, the jet shear-layer vortices, and the counter-rotating vortex pairs.     

The Conjugate Gradient Method in Random Variables

We study the conjugate gradient method for solving a system of linear equations with coefficients which are measurable functions and establish the rate of conve...