用双曲正切和反正切函数拟合面波频散曲线的适应性分析

双曲正切函数和反正切函数的形态与面波频散曲线较相似,将其用于频散曲线拟合可减少数据噪音对反演稳定性的影响。这两类函数的曲线形态都是单调变化的,无法完全刻画某些特殊地层结构形成的频散曲线的复杂变化情形,如果用这两类曲线来拟合频散曲线则会存在本质上的模型误差。通过一系列正演模拟,分别运用这两类曲线拟合随层厚、P波速度、S波速度和密度变化模型的频散曲线,定量分析每个参数的变化对拟合误差的影响。结果表明,拟合结果随着P波速度、密度和层厚变化的分布很稳定,误差值保持在0.03~0.11。在S波速度随深度单调增加的情况下,拟合误差变化起伏比较大,误差范围为0.00~0.14,表明这两类三角函数模型的适应性会随着地层间S波速度差异的增大而降低。当模型中含有一定厚度的倒转低速层的时候,拟合误差可高达0.30,表明双曲正切函数和反正切函数频散曲线模型均不适用于拟合含强烈反差的低速倒转地层的频散曲线。实验发现,严重影响频散曲线拟合的误差突跳难题,可以通过多个随机种子的组合得到有效解决。     

低气压对水体表面张力影响研究

表面张力是液体接触气体时的基本特性。本文设计了低气压下表面张力系数测量装置,研究了气压降低对水体表面张力系数的影响,提出了低气压下表面张力系数计算公式。研究表明,相同水体温度下,气压与水体表面张力系数间呈良好的线性关系,气压越低,表面张力系数越大;气压降低时,气压和温度对水体表面张力的影响是基本独立的。     

半无限一维光子晶体在满足平均折射率等于零时的表面态

运用传输矩阵方法和Bloch定理，研究了以色散介质为背景，半无限一维光子晶体在满足平均折射率等于零条件下的表面波特性，发现在一定的堆积次序下存在群速度为负的表面态，此时表面波的波矢和能流方向相反，并讨论了该情况下表面态的模式简并情况。     

提高单头蜗轮滚刀齿面造型精度的一个数值仿真方法

本文剖折了铲磨单头蜗轮滚刀齿面的数学机理,建立了齿面造型过程的仿真数学模型,并进行了数值仿真计算。数值仿真结果表明,该模型是可靠的,可直接用于实际加工。     

新鲜多孔硅(001)表面结构与电子特性理论研究

在周期边界条件下的k空间中,采用基于密度泛函理论的广义梯度近似(GGA)平面波超软赝势法,建立H12S i31几何模型来对表面主要被H覆盖的新鲜多孔硅(Porous S ilicon,PS)(001)表面最外层的S i—H键的几何结构和电子特性进行初步的理论研究.计算得到氢化PS(001)表面几何结构S i—H键长为0.148 nm、H—S i—H键角为106°,并通过原子布居数、电子密度图分析得到氢化PS表面原子的电子特性.     

InP单晶表面势垒高度与表面态密度的光伏测算

应用变温光伏方法测定了Ｎ型低阻ＩｎＰ单晶的表面势垒高度，进而分析、计算了简并化的ＩｎＰ单晶表面态密度。     

IMPACT OF APPLYING BCTMP TO WOOD-FREE LWC ON ITS PERFORMANCE

INTRODUCTIONBleached CTMP (BCTMP) is popular in many commercial paper grades, such as packaging, tissue, uncoated wood-free fine papers. There is a strong economic incentive to substitute BCTMP for kraft pulp in producing wood-free light weight coated paper (LWC). Wood free LWC is used mostly for high-speed heatset web offset (HWSO) color printing. With a low basis weight and also low coat weight, the strength, surface and structural properties of the LWC wood-free paper are al…     

Grinding Characteristics Of Directionally Aligned SiC Whisker Wheel-Comparison With Al2O3 Fiber Wheel

A unique SiC whisker wheel was invented,in which the whiskers were aligned normally to the grinding wheel surface.In this paper,grindabilities of the SiC whisker wheel are investigated and compared with those of other wheels of SiC grains,Al2O3 grains,as well as Al2O3 long and short fibres which were also aligned normally to the grinding wheel surface,respectively.The main research contents concern grinding characteristics of a directionally aligned SiC whisker wheel such as material-removal volume,wheel-wear rates,integrity of the ground surfaces,grinding ratios and grinding efficiency.Furthermore,grinding wheels of whiskers and fibres have a common disadvantage:they tend to load easily.The authors have proposed a simple method of loading-free grinding to overcome this propensity and investigate some related grinding characteristics under loading-free grinding conditions.     

论多值函数

通过讨论多值函数的典型代表———根式函数 ,运用黎曼面 ,清晰、形象地揭示多值函数复杂的变换特性 ,并论述分出多值函数的各单值分支的关键问题及其方法 .     

STUDY ON THE COLLOID CHEMISTRY BEHAVIOR IN THE ONP DEINKING SYSTEM

1.INTRODUCTIONWith the great rising of secondary fiber in today’s paper market, people has been paying more and more attention to the technology of recycling the secondary fiber. However, in today’s world, the basal study of waste paper deinking is not enough. People lack the systemic cognition of different secondary fiber’s recycling. In this paper, from study on the physical-chemistry behavior in the DIP, we mainly researched the colloid chemical behavior of the pulp coarse disper…